<human>: Can you give me the gist of the text in a nutshell?

Hello everyone, thank you in advance for reading my post. 

As the title says the guy who I've been seeing for a few months had recently met my best friend. We are quite opposite but like sisters. Me, reserved, low maintenance appearance wise and her, a vixen, dressed to the nines and with a bit of a wild past. They seemed to get along but nothing out of the ordinary. 

The issue is they have become friendly, with my encouragement, and seem to talk to each other when I'm not around. He does bring her up constantly to the point that I have been stressed that he really likes her and not me. He notices and seems to enjoy seeing my squirm (all jokingly according to him). 

The thing is she has in the past gone around and hooked up with her friends boyfriends and I don't know if I trust her intentions. I think she enjoys seeing guys fall for her. 

I don't know if I trust him when he says he is not interested in her and is just going to string me along till he gets a chance with her....

I really don't know how to approach it. I feel funny telling him I'm uncomfortable because of her past behaviour because that is talking behind her back.... Loyalty is important to me. 

I am absolutely in love with him. I've known him for about 10 years. Recently re-connecting. He is about a year out of a long term relationship (4yrs) that really did a number on him .. Which is also why I don't like to pressure him (I have commitment phobic tendencies myself). 

Help Reddit!? Do I just deal with it and trust the two of them. Or can I say something to help ease my worries??
Thank you!!
<bot>: Guy I'm seeing talks incessantly about my vixen friend, worried he likes her more than me if he had the chance....