Not exactly. There was a custom in some parts of Ancient Greece where young male apprentices (teenagers) had sexual relationships with their (adult, married) teachers during the time they were apprenticing.

Their relation to sexuality is difficult to compare to our modern one. As I understand it, once they reached “full” adulthood, men were expected to settle down, form a family and all that. I’m not aware of polygamy being a thing.

Obviously, the (male, wealthy) elites that write to us may not be entirely forthcoming about the goings-on within the households. Given that slaves were at the absolute mercy of their owning household’s master, I’m inclined to think that the depictions of their gods as lustful and unfaithful are a projection of their own vices and habits.

What I do know is that Sparta in particular is reported to occasionally have Spartiates “lend” their wives to other Spartiates (but I have no idea how often it would have happened). We’re not going to talk about the women’s consent here… If the Spartans’ practice of sharing their wives was noteworthy, that implies women were otherwise expected to be chaste and faithful.

But men? Like I said, what they did to their slaves wasn’t anybody else’s business.