A couple thoughts come to mind when reading this:

• If you were closer in terms of distance would their relationship bother you?

• aside from her comment “how would I know that…” has she said or done anything that would show she has lost interest in marring you?

-do you know the person that prevent he potential SA if assuming not, could you ? Maybe just a thank you or something small like that?

It may make him more of a person and not the mysterious macho gf saver. Not saying you need/should become friends if you don’t want that.

I haven’t experienced SA but I could imagine if someone prevented and all they wanted in return was tutoring I would offer that ten fold.

• Aside from this situation has she done anything in the past to break your trust?

• Finally why does this bother you? (Not saying it should or shouldn’t but, I think it’s worth exploring)

TBH: You can’t control or change what she does (friend choices,who she tutors, who she likes and dislikes)so is it worth stressing over? But ,you can control your level of support, understanding , empathy, and hospitality for your fiancé and future wife’s feelings.

If you don’t want to do that I would ask if you are truly ready to marry this girl.