Learn Hardcore Japanese: syuumatu ni karesi ga uti ni kite kurete, watasi ga kaimono ni itte iru aida rusuban wo site kuremasita. - On the weekend my boyfriend came over and watched the house while I went shopping.

来てくれて
= 来て + くれて
= “(he) came for me / did me the favor of coming”
してくれました
= して + くれました
= “(he) did (it) for me / did me the favor of doing (it)”

In natural English we don’t usually say “He came for me and did house‑sitting for me,” so it’s often translated more smoothly as:

“my boyfriend kindly came over to my place and watched the house while I was out shopping.”

The くれる emphasizes that the speaker feels grateful / helped by his actions. It adds a nuance of kindness or favor, not just a neutral description of what happened.

Why are there two くれ’s: 来てくれて and してくれました? Are both really necessary?

They’re both there, and both are doing something slightly different.

来てくれて: “he (kindly) came (for me), and …”
留守番をしてくれました: “he (kindly) watched the house (for me).”

So the sentence is essentially:

He did me the favor of coming to my place on the weekend, and (in addition) while I was out shopping, he did me the favor of watching the house.

You could say:

週末に彼氏がうちに来て、私が買い物に行っているあいだ留守番をしてくれました。

Then only the house‑sitting is clearly marked as a favor; the “coming” is just a neutral action.

In the original, both actions (coming over and house‑sitting) are felt as something kind he did for the speaker.

Why is 週末 marked with に (週末に) and not は or nothing at all?

週末に marks when the event happened:

X に → “at/on X (time)”

So 週末に = “on the weekend.”

Other options:

週末、彼氏がうちに来て…
- Dropping に is also possible in casual speech.
- The time word just sits in front; the meaning is still “on the weekend.”
週末は彼氏がうちに来て…
- 週末は makes “the weekend” the topic:
  “As for the weekend, my boyfriend came to my place and…”
- This often implies a contrast (e.g. on weekdays something else usually happens).

So:

週末に → neutral “at that time.”
週末は → “speaking about the weekend (as opposed to other times)…”

The sentence chooses 週末に simply to state when it happened, without any contrastive nuance.

Why does it say 彼氏が and not 彼氏は?

Here, 彼氏 is the grammatical subject of the actions:

彼氏が … 来てくれて、… 留守番をしてくれました。
“My boyfriend came … and watched the house …”

Using が:

identifies who performed the action(s),
can feel a bit more “informational” or “it was my boyfriend who …” in this context,
keeps the focus on who did the helpful actions.

If you said:

彼氏はうちに来てくれて、…

then 彼氏は becomes the topic:

“As for my boyfriend, he came to my place and…”

That would sound more like you are giving general information about your boyfriend (maybe contrasting him with someone else). With が, you are just stating that it was he who did these specific favors.

What is the nuance of うちに here? Could you say いえに instead?

Both うち and いえ can mean “house/home,” but they differ in nuance:

うち:
- Very commonly used in conversation to mean “my place / our home / where I live.”
- Sounds warmer and more personal.
- Often implies “my family’s place” or “my own place.”
いえ:
- More neutral “house/building/home.”
- Can refer to any house, not necessarily the speaker’s.
- In this sentence, いえ would be understood as “my house,” but it sounds a bit more neutral/formal than うち.

So:

うちに来てくれて fits the casual, personal tone: “came over to my place.”
いえに来てくれて is not wrong, but less colloquial/personal.

Why do we have 私が before 買い物に行っている? Why not 私は, or just omit 私?

The sentence has two different subjects:

Main actions:
- 彼氏が … 来てくれて、… 留守番をしてくれました。
  → Subject = 彼氏 (boyfriend)
Time clause:
- 私が買い物に行っているあいだ
  → Subject = 私 (I)

We mark 私 with が because:

が marks the subject inside this subordinate clause.
It clearly shows: “while I was out shopping (he watched the house).”

About other options:

私を – wrong here (を marks direct object, not subject).
私は – possible, but less natural in this kind of embedded time clause; が is standard for the subject of a subordinate clause.
Omitting 私 – very natural in context.
If it’s clear we’re talking about “me,” you’d often say:
- 買い物に行っているあいだ留守番をしてくれました。 and let 私 be understood from context.

So 私が is there to clarify that in that “while…” part, I am the one who is away shopping, not the boyfriend.

What exactly does 買い物に行っているあいだ mean? Why use 行っている, not just 行く or 行った?

Break it down:

買い物に行く – “go shopping”
買い物に行っている – literally “be in the state of having gone shopping”
〜あいだ – “while / during the time that 〜”

So:

買い物に行っているあいだ
≈ “while (I) am out shopping / during the time I’m away shopping.”

For verbs of movement like 行く, 来る, 行っている often does not mean “am in the middle of walking/driving there.” It usually means:

“have gone somewhere and am (currently) there / away.”

Examples:

今、母は買い物に行っています。
→ “My mom has gone shopping (and is out right now).”

So 買い物に行っているあいだ focuses on the whole period when you’re away from home due to going shopping, not just the short moment of physically traveling.

If you said:

買い物に行くあいだ – “while (I) go shopping”
→ This sounds off; 行く is a point-like action, so its “あいだ” doesn’t feel like a natural duration.
買い物に行ったあいだ – ungrammatical as a time expression; you’d say 行っていたあいだ if you want a clearly past continuous sense.

What’s the difference between あいだ and あいだに? Could we say 行っているあいだに here?

Basic contrast:

〜あいだ
→ During the whole period, something is continuously true/ongoing.
〜あいだに
→ At some point(s) during that period, something happens (not necessarily continuously).

Examples:

子どもが寝ているあいだ、ずっと本を読んでいました。
→ “While the child was sleeping, I was reading the whole time.” (continuous)
子どもが寝ているあいだに、本を１冊読み終えました。
→ “While the child was sleeping, I finished reading a book (at some point in that span).” (event within the period)

In your sentence:

私が買い物に行っているあいだ留守番をしてくれました。

The boyfriend is house‑sitting for the entire time you’re away, so あいだ (without に) is the best match.

You could say:

買い物に行っているあいだに留守番をしてくれました。

and it’s not wrong, but it sounds more like “he did the house‑sitting at some point(s) during the time I was out,” which is a bit strange for 留守番, since that is typically continuous.

Why is 行っている in non‑past form when the whole sentence is clearly in the past (してくれました)?

Japanese tense in subordinate clauses is often relative, not absolute. The non‑past there doesn’t mean “present” in the real-world timeline; it means “at the same time as the main event.”

Main event is in the past:
→ 留守番をしてくれました (past polite)
Time clause:
→ 私が買い物に行っているあいだ (non‑past)

This pattern is very common:

ご飯を食べているとき、電話が鳴りました。
→ “While I was eating, the phone rang.”
私が学生でいるあいだ、ずっとアルバイトをしていました。
→ “While I was a student, I worked part-time the whole time.”

You can say:

買い物に行っていたあいだ

This strongly anchors that “going shopping” period in the past as an ongoing state. Both are grammatical; 行っているあいだ is simply the more neutral, natural choice here.

What exactly is 留守番 and how does 留守番をする work grammatically?

留守番 (るすばん) is a noun meaning:

“staying at home and looking after the house,”
“house-sitting,”
or (for kids) “staying home while parents are out.”

As a verb, it appears as:

留守番をする – “to house-sit / to stay home and watch the house.”

This is the common pattern:

Noun + をする → “to do [that noun].”

So in the sentence:

留守番をしてくれました
= 留守番をする + くれる (past polite)
= “(he) did house‑sitting for me / watched the house for me.”

Is を in 留守番をしてくれました optional? Could you say 留守番してくれました?

Yes, を is optional here.

Both of these are natural:

留守番をしてくれました。
留守番してくれました。

Many する-verbs allow dropping を in everyday speech:

勉強(を)する
練習(を)する
掃除(を)する
留守番(を)する

Sometimes one form is more common than the other, but with 留守番, both are very common and mean the same thing. Including を can sound slightly more careful or explicit, but it’s not a big nuance difference.

Could the pronouns be omitted? For example, can you drop 私 or say this without clearly mentioning “my boyfriend” every time?

Yes. Japanese often omits pronouns when they’re clear from context.

For example, if the context already makes it obvious that:

you’re talking about your own weekend, and
you have been talking about your boyfriend,

you might say more naturally:

週末に彼氏がうちに来てくれて、買い物に行っているあいだ留守番してくれました。

Here:

私 is omitted before 買い物に行っている; it’s understood that you are the one going shopping.
彼氏 still appears once at the start to set who we’re talking about; after that, you don’t repeat it, because the subject of してくれました is clearly the same person (彼氏).

In real conversation, even 彼氏 might be omitted if it is absolutely clear from the previous sentence, e.g.:

彼氏ができたんだ。
週末にうちに来てくれて、買い物に行っているあいだ留守番してくれました。

So yes, pronoun dropping is very normal, as long as the listener can easily tell who did what.