Does having a Three Way with a couple count as cheating?

I had an intense argument with a close friend, and now I feel obligated to get more opinions. Three people, all in a polyamorous relationship:<br><br>Man (M)<br>His Wife (W)<br>Girlfriend of M (G) <br><br>So, W and M have been dating for 10+ years. And literally, I've never heard a negative word about their relationship. Before our hangout, absolute lovebirds. <br><br>This winter, M meets G at a conference, and they immediately hit it off. Mutual respect, sexual tension, and before you know it, G is in the picture. I'm not sure all the details about how their relationship developed (I think M and G used to be coworkers), but what's important is M and G did have sex in secret. But, they both agreed that it didn't feel right. When they told W, she was upset because she felt blindsided, but then she realized that she wanted to meet G. <br><br>So, the three of us met up on Tuesday (technically M, W, and G are polyamorous). It was literally a blast, and although the details were light and fun, we had a great time. But G and W had sex. And everyone was blindsided again.<br><br>How did M feel? He was mortified. And I guess with his wife and girlfriend having sex, well, you can't blame him. But, my argument with M is that what happened between G and W shouldn't count as cheating, for a few reasons. <br><br>1. M told me that G was in control. It was like G took charge. So, he can't fault W for being overpowered. It's not like W wanted to cheat, but couldn't control herself. It's not like she wanted to do it for the thrill. She just had sex with G and didn't know what else to do. <br><br>2. M and W's relationship is strong, and they both know it. If you know your relationship is solid, there's no upside to cheating. It's a pointless move. And I think if you know that, and can trust your partner, then you should have that trust. And W trusts G, and so does M.<br><br>3. All parties are happy about it. W is happy because she got to know G on a deeper level, M is happy because he got to see how happy it made W, and G is happy that W trusts her so much that she let G take control. <br><br>So, all well and good, right?<br><br>Except M and I just had a huge argument, and we can't agree. M thinks that if I ever find myself in a similar situation, I'll change my mind. I think it's just a Three Way, and moving on, it just means Three people are Three Ways involved.