What does the なる and the と mean in this sentence

Question

What does the なる and the と mean in this sentence?

でも男のことになると、どうにも弱いとこがあってさ…

From what I have learnt so far:

• と can mean "and", eg. 私は水とジュースを飲んだ

• と can be used to imply an inevitable outcome, eg. 六時になると、太陽が見える

• と can be used to quote a thought or something that somebody said, eg. 「強くなりたい」といったでしょう？

But it seems that the と in this sentence doesn't fit any of these usages.

As for the なる, it usually means "to become", right? But in this case, it says 男のことになる. 男のこと means "about guys", and that is not something you can "become"...

Answer 1

Xになると and Xとなると are synonymous set phrases that mean "when it comes to X..." or "as for X..." They have nothing to do with something becoming something else.

Answer 2

でも男のことになると、どうにも弱いとこがあってさ…

The と is a conjunctive particle (接続助詞) meaning "When" or "If". It's the と in your second example:

と can be used to imply an inevitable outcome, eg. 六時になると、太陽が見える

that is not something you can "become"...

The subject of the なる is not the speaker, but more like "things" or "topic".

As the other poster says, 「～（こと）となると、」 or 「～（こと）になると、」 is a set phrase that means "When it comes to~~" "Speaking of~~".

I would break it down to...

男のこと - matters/issues about men
になる - (it/things/situation/topic) becomes
と - when