teen relationship

so my boyfriend recently met this girl from school, through one of his friends.

•lets call this girl “G”

•we’ll call my boyfriend “B”

•we’ll call his friend “C”

So, C and B have been really good friends for the past year and C introduced G to B, B has been getting really close to G, like REALLY CLOSE, and i’m feeling uncomfortable and slightly losing trust in B. I’ve talked to B about it and C has talked to G about it, since they’ve now been in their own relationship for a couple months, but ever since C and G started dating G and B have gotten EVEN CLOSER, they share secrets they wouldn’t even share with C or Me, and it kind of makes us concerned that B and G have started dating, B and G have gone out on dates and when B and i have gone on a date, B would always mention G, the same thing goes for C, overall, i’m unsure about what to do about this, my friends say i should dump B but i still have feeling for him :(