Learn Hardcore Russian: Моя мама не всегда рада, если я читаю роман всю ночь. - My mom is not always happy if I read a novel all night.

It must agree with the subject in gender and number:
- я рад (a man speaking)
- я рада (a woman speaking)
- моя мама рада (feminine singular)
- мы рады (plural)

So with моя мама (feminine), you need рада.

The form радaя would be the long form adjective and is not used as a simple predicate like this. You normally say:

Моя мама рада. = My mom is glad.
Not: Моя мама радaя. (this sounds wrong here)

Why is it не всегда рада and not всегда не рада? Do they mean the same thing?

They are not the same:

Моя мама не всегда рада…
= My mom is not always happy…
(Sometimes she is happy, sometimes she is not.)
Моя мама всегда не рада…
= My mom is always not happy…
(Practically: she is never happy in that situation; she is always unhappy.)

So не всегда рада means “only sometimes unhappy”, while всегда не рада means “always unhappy”. The original sentence is softer: Mom is annoyed only some of the time.

Why is the present tense читаю used when this seems like a general or repeated situation, not something happening right now?

In Russian, the present tense of an imperfective verb (like читать) is used for:

Actions happening right now
- Я читаю роман. = I am reading a novel (now).
Actions that regularly / usually happen (habitual)
- Я читаю по вечерам. = I read in the evenings.

In the sentence:

…если я читаю роман всю ночь

the meaning is habitual: whenever / when I read a novel all night. Russian uses the same present tense form for both “now” and “whenever” contexts; the context tells you it’s general, not just this one night.

Why is если used here? Could we use когда instead? What’s the difference?

Both can work, but they have different nuances:

если = if / whenever
- Focus on condition: if this happens, then that happens.
- Suggests that the situation is possible or repeated, but not guaranteed every time.
когда = when / whenever
- Focus on time: at the time when this happens.
- Often sounds more like a regular, expected event.

Compare:

Моя мама не всегда рада, если я читаю роман всю ночь.
= My mom is not always happy if / whenever I read a novel all night.
(Emphasis: that’s the condition.)
Моя мама не всегда рада, когда я читаю роман всю ночь.
= My mom is not always happy when I read a novel all night.
(More like: on those nights when this happens.)

Both are grammatically correct; если keeps the “conditional” feel a bit stronger.

Should there be a то after если, like если я читаю…, то моя мама…? Why is it missing?

Russian often uses the pattern:

Если …, то … = If …, then …

But то is optional in everyday speech and writing. You can:

Include it:
Если я читаю роман всю ночь, то моя мама не всегда рада.
Omit it:
Если я читаю роман всю ночь, моя мама не всегда рада.

Both are correct. Adding то can slightly highlight the result (то) of the condition (если), but in this short sentence it doesn’t change the meaning.

What case is роман in here, and why does it look the same as the dictionary form?

Роман is in the accusative case, because it is the direct object of the verb читаю (I read what? → novel).

For inanimate masculine nouns like роман, the accusative singular form is identical to the nominative:

Nominative: роман (this is a novel)
Accusative: читаю роман (I read a novel)

So it looks like the dictionary form, but grammatically it’s the accusative case.

Why роман and not книгу? Does роман mean “romance”?

In Russian:

роман usually means “novel” (a long work of fiction), not necessarily romantic.
книга means “book” in general.

So:

читать роман = to read a novel
читать книгу = to read a book (could be any kind of book)

Роман can also mean “love affair / relationship” in some contexts, but with читать it’s almost always understood as a novel.

What is going on with всю ночь? Why всю and not вся? What case is this?

Всю ночь is:

Accusative case, expressing duration of time (how long something lasts).
Всю is the accusative feminine singular of весь (all / the whole).
Ночь is a feminine noun.

So:

Nominative: вся ночь = the whole night
Accusative (duration): всю ночь = (for) the whole night

Russian often uses the bare accusative (no preposition) to show how long an action lasts:

Он спал всю ночь. = He slept all night.
Я работал весь день. = I worked all day.

Can I change the word order, like Моя мама не всегда рада, если я всю ночь читаю роман? Is that okay?

Yes, that is okay and perfectly natural. Russian word order is flexible. Both:

…если я читаю роман всю ночь.
…если я всю ночь читаю роман.

are correct and mean the same (“if I read a novel all night”). The difference is just slight emphasis:

читаю роман всю ночь: mild focus on роман (what you’re reading).
всю ночь читаю роман: mild focus on всю ночь (how long).

Context and intonation will matter more than this small difference.

Could I omit the pronoun я and just say если читаю роман всю ночь?

You could, but it sounds a bit informal and elliptical. In Russian, the verb ending does show the person:

читаю = I read.

So in casual speech you might sometimes hear:

Если читаю роман всю ночь, мама не всегда рада.

It’s understandable, but in standard, clear language (especially for learners), it’s more natural to include the pronoun:

Если я читаю роман всю ночь, мама не всегда рада.

Could we use a perfective verb, like прочитаю, instead of читаю? What would change?

Yes, but it would change the meaning:

читаю (imperfective, present)
Focus on the process / activity:
Если я читаю роман всю ночь…
= If I spend the whole night reading a novel…
прочитаю (perfective, future)
Focus on the completed result:
Если я прочитаю роман за ночь…
= If I manage to finish / complete a novel in one night…

So:

The original sentence talks about the action of reading all night.
Using прочитаю would talk about successfully finishing the whole novel overnight.

Why say моя мама and not just мама? Are both correct?

Both are possible, but they have slightly different style / feel:

Моя мама не всегда рада…
Explicitly: my mother. More neutral, explanatory, or when you want to emphasize it is your own mother.
Мама не всегда рада…
Often used when it’s obvious it’s your own mother from context, or in informal speech. Russian frequently drops мой / моя with close family members if the context is clear.

In a textbook-style example, моя мама is very natural, because the context is isolated and we want to be clear: my mom.