I slept with a married man I love, why does it feels so intriguing?

[Man-eating WOMBAT]

It feels good because you're putting aside the almost entirely abstract, arbitrary restrictions that society has placed upon you.

Sex has existed for about 3 billion years.

The social myth of "marriage" has existed about as long as the myth of "money."

That is, only about 6,000 years. Certainly not before humans developed agriculture. It really started out as a form of slavery. People created the idea in order to have an flimsy excuse to kill others in a jealous rage. Or even just treat certain people like pariahs, steal their posessions, that sort of thing.

People have been victimizing and exploiting each other, and inventing justifications for it, since we were apes.

Nature trumps abstract social idealisms.

You had the chance to reproduce. You fulfilled one of your most basic goals as a living being.

And yes cheating/ promiscuity benefits women equally as much as it benefits men, and for the same reasons.