Well I don’t think the lesson you’ve learned is a good one. The solution isn’t to stop talking to people. You said you never fit in and then proceed to conclude that it’s other people’s fault. Maybe in this situation it is but it can’t possibly be always other people and other groups who always do things wrong. Of course it’s your choice how to conduct yourself in a group.

It’s entirely possible the woman was uncomfortable with your flirting because she liked the guy and you made a point to emphasize your good looks. But that’s precisely why it is better to flirt in private. No need to make others uncomfortable especially if you don’t know people well. But you don’t need to stop socializing