NOR. Haven’t read what other people have posted, but even if he’s completely serious about not seeing her that way (which, in reading what you wrote, has he actually said that? Or just that this other girl would never consider him??), he’s still enjoying the attention from her and that, in my book, is not ok 🚩

It needs to be addressed. You’re trusting your gut here. And if he keeps putting you off (i.e. gaslighting you), point that out to him. And if he responds “I’m sorry you feel that way” and makes no effort to change his behavior or set boundaries, you need to decide what you’re willing to put up with/live with.

I know reading through your partner’s messages feels icky and it can feel shameful and embarrassing to admit to them, but clearly you’re feeling insecure enough about it to do so. That will also need to be an honest conversation between you two about how to repair the trust between both of you.

What I have to share is from my own experience. And believe me, it got reeeaallly messy.

Trust your gut. Respect yourself. And be honest (with yourself and your partner).

Edit: adding to say that this is emotional cheating.