Boyfriend problems

So I really need help on this cause I'm not sure what to do. My boyfriend and I have been dating for 7 months now and for the past couple of months we have had some issues with me getting upset about talking to other girls. (yes I'm a very jealous person) but normally I can handle myself but there is this one girl that he is friends with and I found out a couple weeks back that she is in love with him and she believes that he is in love with her. I told him and he still kinda hangs out with her I don't think he's cheating but I'm not sure how to get around this. I believe him when he says there is nothing going on but how am I supposed to just be okay with this? HELP?!?!