That said, you don’t have to act on your feelings. Lots of times people get the idea that just because they have a feeling, they need to stop traffic, announce how they feel and act on it. Not true. Sometimes it’s enough to acknowledge your feelings and sit in them. Discomfort isn’t pleasant, but it can be a place where you can learn a lot about yourself.
Be careful not to get into a fight with your boyfriend by accusing him of doing something he hasn’t, like cheating on you, with this girl. You can tell him how you feel when this other woman is around the two of you — that you feel left out and like a second class citizen, and you wish that maybe he could take your hand or put his arm around you when he’s talking to her. This might make you feel more secure, while allowing him to talk to this girl, while showing her that he belongs to you by his body language. Something as simple as that gesture may solve the problem. And if he does go along with this, thank him and reward him!
Just don’t back your boyfriend into a corner and put him on the defensive when you discuss this with him. If he feels blamed, he’s going to get defensive on you. But if he feels like you’re sharing feelings and asking him to help you with a problem, then he may feel like this is something he can fix, and men love fixing things because then they’re the hero.