Am I understanding right? You work long hours to pay all the bills while she does very little in the way of chores or helping out, spending much or most her time, rather, with other boyfriends, as often as not forgetting one small request of advance notice for staying out overnight...and she's telling you she's really the one working the hardest in this relationship? And you're constantly apologizing for being difficult when you're supporting her and asking virtually nothing in return?
What exactly is she working so hard at?
What are you getting out of this relationship?
To me, this sounds like an abusive relationship.