Are these friends of yours telling you he is likely cheating, or coworkers spreading gossip? If they are friends, trust them. There is a difference between information and rumors, usually it’s the source that differentiates.
Wait… why would you message the girl? She has nothing to do with this.
My honest opinion? Move on. Doesn’t sound like it was a very happy relationship for a few months anyway and I hate to say it but it sounds like he’s moved on. I been in a similar relationship and I know it does and will hurt like hell but it’ll get better with time and you’ll meet someone whom you don’t need space from to figure things out soon enough.
I don’t know a lot of people that had “breaks” that work out. It also sounds like he is considering it a break up. He is moving on.
Since those are YOUR friends that work with him I would trust them. do they have some reason why they would lie about this? If they’re your friends they have your best interest at heart.
He’s telling people he’s younger, he had a HICKEY confirmed by 3 people, he’s been spending a lot of time with what’s-her-face. Honestly he sounds kind of like a piece of shit. That seems to be a lot of smoke there must be some fire.
You guys are on the rocks anyway just break it off already. It does look like he’s already moving on. If you guys patched things up will you really be able to trust him? What were the issues you guys were trying to get through?
I would break up with him and then take that space for yourself and really think about your worth and the kind of relationship you want.
It sounds like he’s making a backup plan for when you guys break up officially.