Pretty much on a daily basis there are women (and men) who suspect that their partner is spending time with a member of the opposite sex.
The OP who it seems is looking for reassurance that it’s quite normal for men and women to be friends and that they are being paranoid... instead this is what usually happens:
LTB he is having an affair
LTB is he probably going to have an affair
LTB remember that time in 2004 when you caught him wanking to a lady gaga video
Nobody really knows what they would do in that position and the advice on here seems very black or white (of course you get the posters who offer genuine empathy)
AIBU to suggest that a lot of advice on here is not the best?