Ok so heres the quick overview:
Theres a HB9 model that goes to my uni. She broke up with her bf about a month ago, but has been "seeing" a guy for like 2 weeks (basically they just hook up and shit). But they def not in a relationship so shes still fair game

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I have been working it well with her and I can tell she wants it too but everytime I am about to make a move, this dude comes in and they eventually make out somewhere. I don't know what exactly to do because I know this guy a little (but barely) so I thought it would be weird to just hook up with her in front of him. I don't really care anymore because I am leaving London in 5 days so I will never see her again. I am planning to just caveman it up tonight when I see her at a party. I swear I was just about to k-close her last night, but at that exact moment the guy came over to talk to her. Even when they were together I saw her giving me strong eye contact, which I naturally returned and took as a good IOI.
I need to make my move tonight so I wanted to know if you guys had any advice on this situation, like if I should just go straight in and k-close or if it even means anything if I kiss her in front of the other guy *I don't want to fight...but I can probably beat him up

I would be most grateful!!