There's a common misconception that [some] men are so flooded with testosterone they are incapable of staying faithful. These men are simply "hardwired to cheat"... and women just need to learn to live with it. Two words: Bull. Sh*t.
Nothing wrong with men (or women, for that matter) dating or being romantically involved with multiple people. What's needed is the integrity to state their intentions honestly to the people they are involved with — instead of hiding, lying, cheating and manipulating. The cold, hard reality: Those who "can't remain faithful" are not only lying to everyone they are involved with... they are lying to themselves. These people simply don't have the courage to stand up to their partner(s) and say: "Hey. I'm not happy and I need to do something/someone else" or "Look, I'm just not in a mental/emotional place to be in an exclusive relationship right now."
It's a choice to honorable and be upfront about monogamy. Not being upfront is either a I-want-my-cake-and-eat-it-too mentality... or cowardice. And to the guys who say, "Whatever! I got lotsa bitches! I don't need to tell them sh*t! I'm a player!" Firstly, you need "lotsa bitches" because the moment one hears you calling them "bitches", you'll need to move on to the next one. Secondly, you're not a "player"... you're a manipulator who lies to get laid in an effort to bolster your self-esteem and sense of masculinity. If you were real, you'd be able to be up front about your intentions and tell the women you are involved with that you aren't exclusive with them... that way, everyone is playing by the same rules. But you can't... because they would dump your ass in a heartbeat... so you have to lie. Nice try, Champ.
Bottom line: You don't need to be in a monogamous relationship... you just need to have honor and be honest about your wants and intentions. That way, everyone keeps their integrity and self-esteem.