Most Helpful Guy
It's unreasonable; if Sean wants to stay with u, he is going to have to accept your "flirty " relationship with Dylan, and the fact u had sex before.
Most guys will be eventually able to get over a sexual relationship with a current male friend in my opinion.
However, he (as well as most guys) aren't going to tolerate his girlfriend, having a "flirty" relationship with ANY guy, especially one she's fucked.
You need to grow the fuck up, and not have "flirty" relationships with guys, out of respect of your relationship and your man's feelings.
Otherwise, you will never keep a guy, AND you'll have a "dirty slut" reputation that will follow you. I also must add this label, once imprinted, is very hard to shake off with the male population.
Change starts today.
Cut out that flirtatious nonsense with Dylan, and every other guy u do the same with!