I feel like if there is even one other man present, they go for him rather than me.

The most recent occurence was at an athletics meet at college, a girl came up to me during the warmups and said hi, we spoke for a few minutes about our courses, who we knew etc. Some guy walks up in the middle of my sentence and says 'Hi' really loud and immediately shes talking to him, she starts laughing at their conversation and slowly their backs turn towards me and I get shut out, they end up running together and talking the whole session. I dont think she ever looked at me again.

Its like no matter how hard I make her laugh or how much of a connection I think we have, the moment another man enters and begins talking I just stop existing, and I see them later laughing harder and connecting more intimately than I ever did. I even had kind of a date a few weeks ago and I was showing her my flat, then my other flatmate gets home with two guy friends, immediately my 'date' is talking to them, she ends up on the sofa with them talking animatedly, I just left and went to my room because there was no point in me being there anymore, I heard her giving one of them her number later on. I have no doubt she ended up fucking him, but I never spoke to her again so I didnt find out.

How the fuck do I maintain a womans interest to the point where she doesnt instantly ignore me when any other option appears? The thing is I listen to their conversations and they dont seem particularly interesting or funny, but like she just knows hes better somehow. Im getting paranoid to the point I dont even attempt to speak to women anymore, I just let everyone else get along to avoid that bitterness afterwards.