Live together vs. Sleep together

If you two live together, --- you have proves that you paid household bills (including half the rent/mortgage), After 6 month, you can ask the guy pay your kids support, it does not matter if the kids are not his or if he was notified before-hand that you had kids or not.

If you paid his tuition, you can ask he pay you back if he got a job because of his education.

If you did not pay equal amount for the living-together, you only sleep with that guy, you probally would not able to ask for any compensation. He might able to ask for you to pay back half of his expense.