Hypothetical: Is it alright for a gay man to start dating, or even marry a woman?

Scenario:
A gay guy, decides he wants to settle down and have some kids. He decides that doing this with other men would be too difficult, or too expensive.

Is it ok for him to start dating women?

Assuming he never cheats, and truly does love the woman, should he ever under any circumstances reveal that information?
If so, when?

Is this fair to the woman, if the man is completely content?

What about the children?