Thank you I am happy if it does make sens! To add a little to my theory (with the beginning) this is how I "see it" being MC doing the rejection.
Mc or ML: Wait... Hold on
Mc or ML: what did you just say
clearly bubble link to ML: So you re saying... ahh (pannel show him being awkward)
Mc or ML: I always thought this kind of thing only happened to other people...
Mc or ML: But now that I'm actually dealing with it firsthand..
Mc or ML: I have to say.. it's a pretty disgusting feeling
Except for the "bubble link to Ml (so you're saying and the ahh) we don t know really who is telling what.
So let's say before that scene, ML confess to MC and MC react like "disgusting" or another kind of harsh reaction. Mc and Ml clearly had a strong friendship (as we can see with the photo Ml will show to Mc) so Mc kind of feel betray because Ml have more than "friendship feeling for him" and Ml understand that this is not "mutual" and became "awkward" then we add what we have
ML: wait hold on, what did you just say (aask about Mc reaction, and confirm this is not mutual)
Again Ml: so you're saying ahh (understand the rejection)
pannel showing Ml feeling "bad"
Mc: (repeat what he mean) I always thought this kind of thing only happened to other people... But now that I'm actually dealing with it firsthand... I have to say.. It's a pretty disgusting feeling.
It could also be Mc saying the first part "wait hold on, what did you just say" (like did you just say you have feeling for me)
Ml so you're saying ahh (understand this is not mutual)
Showing Ml feeling bad
Mc explaining his reaction (I always thought ...)
A scene like this would make sens with Ml drugging Mc and making him believe they were in a relationship.
ML clearly does have feeling for mc it would make no sens for him to reject mc, drug him faking a relationship and needing to hold back! If ml was the one who did the rejection he wouldn't have to go that far and "hold himself back later on" and it wouldn t make sens either to sleep with him while calling it "it's a pretty disgusting feeling"
It make 0 sens if Ml did the rejection
It make 100% sens if Mc is the one doing the rejection at the beginning!
And yes I put too much time on analyzing this scene! I don't like not knowing!

Oki maybe you all saw it already and I am like "OMG REVELATION!" BUT
Just in case!
On the cover picture!!! ML hold a syringe and MC have a dark spot on his wrist!! ML DOES INJECT MC SOMETHING!!!!
ML clearly is the one that want a relationship with MC! (tell himself he need to hold back and all) The rejection at the beginning, I am calling that out, its probably from MC! But this is missleading because we don't see MC "link with the bubble" So the one who is saying that "this is disgusting" is probably MC!! NOT ML!!!
So ML confess, MC rejected, ML drug him and created the memory lost! The accident alone wouldn't guarantee a memory lost! They are working in a pharmaceutical lab! This would explain also why ML feel uneasy with MC choosing a movie that he would found "disgusting" normaly!!