You just need to assertively tell these guys that you have a boyfriend and you're not interested. If they don't respect that, you should remind them once and only once of what you said and that you won't be interested in hanging out with them again if they persist.

Today, one of the other guys in the group (let’s call him Y) asked if I was going to come hang out, and I told him what happened. Even though he’s been best friends with X for years, he was PISSED. Apparently X has asked Y to lie to X’s girlfriend a lot, which Y thinks is shady.

Tell him, but make sure he doesn't go and beat up on the other guys. Telling him now, rather than him finding out in a month, will difinitely make the situation easier. Honestly, having been the guy in this situation, I would rather know.

Should I Tell Him I’m Dating Other Guys? 11 Things to Consider 1. Tell him right away. If going out with several men (two or three) in your search for the right one is your strategy, it only makes sense to let your date know right away (on the first date even) what you’re up to. The perfect time to tell him is in the beginning, it’s safer ...