Responses
No. The guy is not the one cheating. Meaning that he is not commiting adultery. He sees a woman who already has someone elde. "Laying your hands on another's will make no one happy" The "someone's" is the short form of "someone elses", wich means "someone who already belongs to someone else".
Hope it is clear now. The dude isn't cheating.

So..... He can not love any woman and cheat them because his friend rejected him???? (〜 ̄△ ̄)〜
And I hate this talk of not being able to stay with the person you love because you want him to have a normal family... This is so depressing, especially when the person likes you too...