My best friends best friend likes me what do I do?!?!

Ok so basically about 9 months ago started dating somone and then we decided to go to a hockey game together and we met up with his friend me and my boyfriend at the time where cuddling and all that and his friend was kinda third weeling a little later we broke up because the age gap but me and him and his bsf became rlly close liek a group and now my ex is my bsf and I wouldn’t trade him for anything and his friend is not as close but his friend likes me and I kinda like him but its weird to talk to my bsf about it because we always hang out and idk if he approves of it and I also know that there is still feelings between me and my bsf because every talk about how we wish we where closer in age so we could date and stuff so idk do I go for his friend or do we all stay friends?