Since you’ve only been dating a month — you shouldn’t worry, [b]but[/b] you also shouldn’t have a commitment yet. It’s way too soon to know each other well enough to say you’re official. Committing too quickly, like you’re doing, puts pressure on the relationship to be monogamous before you know enough about yourselves as a couple. In fact, you’re feeling that pressure right now! The reason you’re worried about this other woman is because you really don’t know him well enough, he doesn’t know you well enough and you’re right that he and this other woman don’t really know what’s going on with them well enough for ANY of you to be in a committed relationship. So here’s my advice: Take the pressure off yourself and the relationship. Relax. Date each other and play the field (knowing he’s doing the same… ) and use the dating process to really get to know each other. Give yourselves three months of dating to see if you even want to continue seeing each other. If you do, then use the second three months to see if you want to be monogamous. Hope that helps!