Need advice about my gfs guy friend hitting on her (post history has some backstory too)

(Sorta) TLDR of my old post: my gf (18) of 2 years made a guy friend within the first days of university who she shares a class with. Im an insecure person and have been known to be jealous so i was uneasy but gave her the benefit of the doubt Especially considering how transparent she had been. Time goes by and she stopped acting so transparent, started hanging out with him alone (a previously set no no for us) skipping classes together and sometimes lying/being sketchy about them hanging out together.

TLDR of this post: my gfs guy friend is straight up hitting on her and while she isnt engaging him she isnt stopping it, telling me about it or reacting negatively (just sends a 😂 likes his messages and moves on) after she knows im already a bit uncomfortable with that particular relationship and had an argument about her lying to me about her company/school life. Idrk how to feel or what do if i even should do anything

So after my gf became very close friends very quickly with a guy she met at University i tried to suppress my previous trust issues and let her embrace this new freedom without being my overbearing self. Early on she recognized that it was the type of thing that would normally bug me a little bit, so she was very consistently and vocally transparent about what they did who was all there (because we had a sorta rule about not having 1 on 1 hangouts with single people that we don’t mutually know with reasonable exceptions like work, class things, parties, etc.) after a while she stops updating because she had privately been hanging out with this guy and didnt want to tell me including getting breakfast hanging out and having lunch daily plus sometimes skipping classes together to hang out. I saw some very questionable “jokes” he made towards her on her instagram and decided it was a solid enough point to justify having a conversation and checking some suspicions and feeling out what was up.
She tells me about how its just jokes and she doesnt encourage it anyways, she does “😂” at all of them and hearts the messages but i accepted her point that she didnt respond positively and moved on.
We talked about how she was lying to me about things and she said she was scared of my reaction if she did tell me (ive never even raised my voice at her and even our “arguments” are very calm civil and always focus on constructiveness so idk why shed be scared enough to hide it) and we both agreed that she would try and be transparent and set boundaries and I would be more relaxed about her activities and friends and such.

Well its been a minute and he’s sending blatantly sexual memes/jokes like about how he looks great naked and she needs to see or jokes about them being sexual, texting her at 11:30 about how NNN is killing him and he wished someone would help, and even had a convo where he “let her in on a secret that guys don’t care about boob size and it’s all about shape and feel” after she mentioned, it was one of her insecurities in Conversation he talks about how “she has great boobs a great ass and given how they jiggle its more than enough”and asked “what is you bf not complimenting them enough?” Now ik a lot of this can just be bro-ish conversations but she talks to him more than ive seen her talk to any girl friend ever and it seems like shes gotten uncomfortably close with this guy and idk how to feel what to do or if anything, even needs to be done, considering she hasn’t directly engaged anything he said (except the boob/butt convo)

i feel like at the very least he doesnt respect the boundaries of our relationship and she never seems to express them. idk what to say but this feels like something I should address so really I guess I’m looking for whether or not my feelings are valid and how to go about handling them without damaging my relationship.