I know it can be hard sometimes because you could potentially not end up feeling like a girlfriend but more like a third wheel... It sucks and its hard to deal with. But if you and your boyfriend have true love for one another then you will know that one rule in a relationship to make it last is "trust". If you can't trust him now with his bestfriend how would you be able to trust him with another woman in the future? If say you marry him? And he works closely with a woman at work. How are you going to cope with that? The easiest way you can deal with this fear is by making a list of positives and negatives.Write down the things that he does that makes you love him so much on one side.. and on the other side write down the negatives of the feelings you get when he is around her or with her without you.If the positives beat out the negatives then you should realize how much he loves you and how much he wouldn't ever want to hurt you.. But if its mostly negatives then you'll realize that you have a fear of being left and that your trust in the relationship isn't as strong as you think it is. And at that point you will have to sort out what you want to do about it.Also, if that doesn't help you should just talk to him about her. Ask him to tell you a bit more about her. Like how long they have known eachother and what he likes about her. But don't nag at him and turn it into a fight. Also what you could do is hang out with the two of them. See what she does. If she respects your relationship she wouldn't be holding onto his arm around you or in public, and she wouldn't act very flirty and cute infront of you. If she does do that then you can have a talk with your boyfriend about how she doesn't respect your relationship at all.I know its hard but sometimes you have to literally just let it go.. I was in a similar situation with my boyfriend and the girl he worked with was just a nightmare. He took her side at first but after a while he realized that he was wrong and that he should stay close to me and be on my side. So i know what it feels like. And it sucks.. But i just had to suck it up and forget about it.hope this helps
