“I know you’re talking to/seeing other guys- we’re done”

When a guy (who you’re in the early-ish stages of dating/ not official yet) says this to you... do you think it’s just an excuse to break things off or could he actually be thinking this/insecure about it?

I was backing off a bit from this guy before he said this bc I wasn’t sure where his feelings were for me but I just feel like why wouldn’t he have a talk about that instead of saying this to me and breaking things off?