Yes, actually, you do see several species partner for life. And using an animal as an analogy to justify human behavior is always a piss-poor excuse.
Exactly, it goes both ways. If you don't want her cheating on you, you don't cheat on her. There's no way around that. Just because you don't get caught or the other party doesn't know about it doesn't make it not cheating. Maybe you try to tell yourself this stuff so that you can justidy living such an immoral and sleazy life, but you <b>are cheating on her</b>.
And not using condoms? How stupid can you be? You get a girl pregnant, you're responsible for the baby, regardless of your feelings on the subject. And no, not every girl is going to want to get an abortion. Not using a condom ranks your intellegence with that of a rock.