So I'm not into the nonmonogamy lifestyle at all and don't really know much about it. I'm currently single and started hanging out with a friend from work (after work drinks etc).

He has a gf which I knew about. Fast forward a few weeks and I leave that workplace and the night I left there was definite flirting from his side, I asked if he was in an open relationship and he confirmed, so I thought why not if all above board. We only kissed but hung out until the wee hours.

We've caught up a few times since and there's alot of texting. Him initiating majority of the time. I asked him last week after a concert what are the rules and how does this work with his gf. He said he hadn't told her about me and it's the only time he hasn't.

Surely this is dangerous territory for him and I reiterated I've no idea what to think about the whole thing and that I don't like to share etc. I know myself pretty well. He was pretty open that his relationship has changed as his gf now wants kids and he's staunchly against it.

Just trying to gather some insight before I progress things any further. We have a great time together but it feels different to dating "single" people as ordinarily I wouldn't know about their other dates etc. I know this guy goes home to his gf etc.