Drive-by flirting

So today, I got this story from a friend of mine and wonder... REALLY?!

So I see this guy and think he's cute. Notice him checking me out and finally he comes over and starts talking to me, really flirty, this goes on for almost an hour. Then he says he has to go "tinkle" and when he comes back from that and talking to his friend, he's all, I have to go get a burrito. Bye. I am of course, totally confused by this exchange and I said so to my friend, who was talking to another guy from that group. That guy (who was actually super nice) tells me, yeah, he's engaged. What was really funny is he tells us that anytime we are talking to a guy who seems into us and it ends like that, we should just assume the guy is engaged, cause that's how guys are.

True? False? I need to know these things...