heya no moyougae to interia ni tuite hanasite bakari iru.

部屋の模様替え means rearranging the room or redecorating the room.

• 部屋 = room
• の = links the two nouns
• 模様替え = changing the arrangement, redecorating, refurnishing

So 部屋の模様替え is literally something like the room’s rearrangement/redecoration, which in natural English becomes rearranging the room.

模様替え（もようがえ） usually means changing the look or arrangement of a space.

It often refers to things like:

• moving furniture around
• changing curtains or decorations
• giving a room a new style or atmosphere

It does not necessarily mean a major renovation. It is often more like redecorating or rearranging than completely remodeling.

Here, の connects two nouns.

• 部屋 = room
• 模様替え = rearrangement/redecoration

So 部屋の模様替え means the rearrangement of the room or the room’s redecoration.

This use of の is very common in Japanese for noun modification. English might use:

• of
• 's
• or just a noun-noun combination

depending on what sounds natural.

インテリア is a loanword, borrowed from a foreign language source and used in Japanese to mean interior or interior design/decor.

Katakana is commonly used for:

• foreign loanwords
• some sound effects
• emphasis
• technical or modern-sounding terms

In this sentence, インテリア probably means interior decor or interior design, not just the inside of something.

と is joining two noun phrases:

• 部屋の模様替え
• インテリア

So it means and.

The sentence is talking about two topics:

• rearranging/redecorating the room
• interior decor/design

So 部屋の模様替え と インテリア について means about rearranging the room and interior decor.

について means about, concerning, or regarding.

It attaches to a noun and marks the topic of discussion, thought, writing, etc.

So:

• インテリアについて話す = talk about interior decor
• 日本の歴史について勉強する = study about Japanese history

In this sentence, 部屋の模様替えとインテリアについて means about rearranging the room and interior decor.

Because the two topics are grouped together before について:

• 部屋の模様替え と インテリア
• then について

This means about A and B.

Japanese often does this when one grammar pattern applies to multiple items. It would sound repetitive to say:

• 部屋の模様替えについてとインテリアについて

That is not how you would normally say it.

〜てばかりいる means to do nothing but..., to be always..., or to keep...ing, often with a slightly negative or critical feeling.

So:

• 話してばかりいる = keeps talking / does nothing but talk / is always talking

In this sentence, it suggests the person is spending too much time talking about these things, instead of doing something else.

Yes.

• 話している = is talking / talking
• 話してばかりいる = is always talking / does nothing but talk

The addition of ばかり changes the nuance a lot. It adds the idea that the action happens excessively or repeatedly, often to the speaker’s annoyance.

So 話している is neutral, but 話してばかりいる often sounds critical.

Not always in exactly the same way.

ばかり often has meanings like:

• only
• just
• nothing but
• always doing

In 〜てばかりいる, it means something like doing that all the time or doing nothing but that.

So here it is not simply a factual only. It carries a feeling of imbalance, like:

• That’s all they ever talk about.

Usually, yes, at least a little.

Because of 話してばかりいる, the sentence often implies:

• the person talks about it too much
• the speaker is annoyed, unimpressed, or mildly critical
• the person may not be doing anything except talking

It does not have to be harsh, but it is generally not completely neutral.

Japanese often leaves out the subject when it is understood from context.

So this sentence could mean:

• She keeps talking about rearranging the room and interior decor.
• He is always talking about redecorating the room and interior design.
• They keep talking about room rearrangement and interior decor.

The subject is omitted because Japanese does that very naturally when the context makes it clear.

The いる here is part of the grammar pattern 〜てばかりいる.

More generally, 〜ている can express:

• an action in progress
• a continuing state
• a habitual/repeated action

In this sentence, because of ばかり, it gives the sense of a repeated or continual habit:

• keeps talking
• is always talking

So いる helps create that ongoing/habitual feeling.

A simple breakdown is:

• 部屋の模様替えとインテリアについて = about rearranging the room and interior decor
• 話してばかりいる = keeps talking / does nothing but talk

So the full structure is:

[topic of conversation] + について + [keep talking]

That gives the whole meaning: (Someone) keeps talking about rearranging the room and interior decor.

Yes, it is natural.

It sounds like something someone would say when describing a person who is very focused on room decor, often with a slightly annoyed tone.

Depending on context, a more casual spoken version might also drop spaces entirely, since Japanese is normally written without them:

部屋の模様替えとインテリアについて話してばかりいる。

That is the standard written form.