A couple of points for future readers:

First of all, there are only two really sacred relationships: engagement and marriage. ESPECIALLY MARRIAGE. If this man were married, I'd urge you to run to the hills.

But he's not married, he's only "dating" this woman. - which leads to the second point.

Women have this idea of "serial monogamy" in dating. We want to date one guy at a time. You are talking about trespassing on some other woman's turf as if she had a moral and legal claim on him, and so long as he hasn't singled her out with an engagement, no such claim exists.

Guys are social daters; they can date a variety of women at a time until they locate the one they're ready to hone in on, court, and marry.

Think of it as using birdshot rather than a rifle bullet - covering a wide area with little impact (except to the birds).

So I don't have a problem with his dating another woman and you at the same time.

What I DO have a problem with is that he's making excuses and not being straight-up with you. Of course, to give him some credit, women just don't understand these things, generally, so he may be winging it on the hoof to try to maintain some level of "esteem" with you.

Ask him. "Are you courting her?" Courting implies moving toward exclusivity, looking at a woman as a very possible/probable marriage candidate.

If he says, "Naw, I'm dating someone, but..." then he's probably safe to date, and you can accept his calls and invitations without violating any higher principle.

Good luck!

Is it fair to automatically penalize a man for not seeing things from a woman's perspective?

What the girlfriend assumes is not so much the issue as what he has TOLD her, or PROMISED her.

I just don't buy into this woman-dominated notion that men are our possessions and that we get to control how they spend their time, who they see, etc. - And if he's promised to be exclusive, then - I'm sorry, maybe it's because I'm a 50-year old "old bat," but I think Miss Manners is right - you're not officially in an exclusive relationship unless you're engaged. That means - a public statement, complete with ring (maybe) and date-setting.

Unless you've got a public commitment, you don't have an exclusive relationship.