OP, I've been in your situation before. One month in, we had the exclusivity talk and she seemed over the moon to go exclusive. A few days later, I was like, yeah, I just remembered I ought to go and delete my OLD accounts. (I hadn't logged in since shortly after I started seeing her.) I expected her to say she'd do the same. Instead, she said, "no, don't delete your accounts! You can use OLD to meet new friends!" I thought that was a weird thing to say - note this wasn't Bumble BFF. We reached a compromise, of sorts: We'd leave our accounts up, but would stop logging in. It made no sense to me, but I thought I could live with it.

Another week or two later, after introducing her to my friends, I started to notice she got uncomfortable whenever anyone referred to her as my GF. I also noticed she never called me her BF. I decided to log back in to my OLD accounts and look her up - and lo and behold, she'd been logging in regularly despite her pledge to stop using OLD.

I'm ashamed to say I never confronted her and stuck around for another month. I really liked her, and was reluctant to face the truth. I rationalized to myself that it must be her phone logging her in to her OLD accounts automatically - she wasn't actually logging in. But I didn't dare to ask. Eventually she broke up with me, explaining she wasn't actually ready to commit.

So, OP, don't do what I did. If your supposedly exclusive SO refuses to stop using OLD, accept that she's unwilling to commit, and leave her. I'm sorry.