I don't think it means he's tired of you. While I disagree with the new age sentiment that thinks this is cool behavior (infidelity in any form), I think that men are hardwired to want as many mates as possible. That said, it takes a good man to appreciate what he's got with a woman. Tell him that exactly, and tell him you wouldn't feel comfortable with it. Saying the same thing vice-versa back to him doesn't always get the point across because it can be seen as petty or an attack (even if it isn't). I think you should just stand your ground. I think if he respects you and is worth your time he will overcome this and take it back.
I don't think it means he's tired of you. While I disagree with the new age sentiment that thinks this is cool behavior (infidelity in any form), I think that men are hardwired to want as many mates as possible. That said, it takes a good man to appreciate what he's got with a woman. Tell him that exactly, and tell him you wouldn't feel comfortable with it. Saying the same thing vice-versa back to him doesn't always get the point across because it can be seen as petty or an attack (even if it isn't). I think you should just stand your ground. I think if he respects you and is worth your time he will overcome this and take it back.