Meaning：
a subject which causes unpleasant memories of past difficulties and arguments

Examples:
A very similar phrase to this is ‘touchy subject’, or ‘a no go area’.
They both have the idea that it is something that you should not really talk about, a sore point is really something that is unpleasant for somebody for a particular reason.

Sentences：
Don’t ask him why he had to sell his car last year; it’s a sore point with him.

Don’t speak about what happened on holiday last summer; it’s a sore point with her.

Don’t ask Fukuda-san if she got a salary increase this year; she didn’t, and it is a sore point with her.

Conversation 1
A: Hi there, have you seen Jane?
B: No I haven’t, why do you want to see her.
A: I heard that she split up with her boyfriend.
B: Yeah, that’s right, about a week ago.
A: The thing is, I lent him some CD’s, and he said that he would give them back to me through her, but if they are not seeing each other that could be a problem so I wanted to get his number off her so I can call him myself.
B: Oh I see, I’d wait a little while before you ask her, the subject of him is a bit of a sore point with her, she’s still very upset about what happened.
A: Ok then, but I can’t leave it for too long because I need my CD’s back.

Conversation 2
A: Hi, what’s the matter with Sarah?
B: I don’t know, what happened?
A: I was just talking to her and she started crying and walked off.
B: What did you say to her?
A: Nothing, I just said that I would rather die than go for dinner with that guy I met in the bar last night.
B: Didn’t you hear, her grandmother died yesterday, so it’s a sore point with her.
A: Oh no I didn’t realize, what a stupid thing to say! I’ll go and apologize.

(Callan book4, Stage 8 799p)