Advice from the old lady:
Date unattractive women who nobody notices. This will cease to be an issue.
Oh wait. You want an attractive girl? She’s had to learn to deal with (often excessive or unwanted) male attention. And you got an “F” in mindreading as well. Guys with this concern are either low value or insecure or both. You do not know what someone else is thinking.
Now. If she’s holding someone else’s hand or kissing/cuddling with someone else? This is physically observable behavior and yes you might have a point. Just understand that EVERY dude is trying to get with a hot girl. So if you find your girl hot? Guess what? So do others. I’m a gregarious person, outgoing and social. Men always want to acknowledge me and sometimes hug me to say hello (if I know them). It’s a nuanced thing to understand as a woman but women who get lots of male attention inherently must learn to manage this, because it’s going to occur (the attention).
If you’ve never dated or been around beautiful women it’s going to be an adjustment to calibrate to how she deals with the attention. You cannot reasonably expect her to be rude or ignore everyone (that’s rude and has adverse effects) or expect her to be a b itch to everyone else either.
I get approached constantly. My boyfriend understands this. This morning actually he joked with me about how many men would try and hit on me (we are attending an event for the sport in which he is semi-pro this week and so will be around lots of other participants)…I always politely shut them down nicely by saying that I’m here with BF. I’m nice but matter-of-fact about it. Everyone knows who I’m with in short order. But there are advantages conferred to my BF because he’s with a socially adroit partner as
@2Rocky alludes to above. If I averted my eyes and refused to interact with anyone whatsoever that would be awkward and weird.
So be sure this isn’t your own insecure nature, OP. It’s either that or low interest on her part. And there are likely other observable signs if it’s low interest. Dismiss for low interest. Check your own insecurities if she’s into you.
My .02