I've been dating a woman for 7 months. She has an ex that follows her on social media and she follows him back. He has a way of sporadically leaving messages under her post... She doesn't seem to encourage or discourage him either. As a means to cope I told her I wouldn't look at her social media profile anymore as she said it was me being insecure.  She has an exhibit coming up next week and she is promoting it on her profile and the ex replied "this seems interesting" she responded " hope to see u there " I haven't mentioned to her that I saw it because I technically told her I wouldn't look at her page anymore. My concern is I'm attending the event as well and it just seems messy for me to go.. I don't know how to address this with her without seeming insecure.

ditto from above message. Move on! "Hoping to see you there" isn't something someone would say unless they meant it.

Really, you're overreacting.  So what if a friend of hers said he'll see her at a place, especially when  you're going too.  Just be mature and greet him the way you'd greet any friend of a friend.  Jealousy is very unattractive.  Confidence is sexy.

On the one hand, you might be overreacting. But if she was truly vested in your relationship, she wouldn't be in contact with her ex, especially knowing that it makes you feel uncomfortable.  But I could be wrong.

7 months isn't a long time now in days.  If she still have her on social media than something must be going on.  Unless they have a kid together but even than they should be following each other.  I'd say move on as well, especially if she put the wink emoji.