Is it wrong to ask?

Me and my ex were broken up for 7 months, during this time we didn’t think we’d ever want to work on things but here we are.. the thing is I found out he would go out in a group with some girl he use to date before me.

I just wanna know the truth if anything happened between them just because when we were together she’d cause us problems.

I just want to know for I won’t look stupid

Is it wrong for me to ask?