Will you help me solve this roommate problem?

I live in a 2 bedroom, 2 bathroom apartment with my roommate. We split the rent and all the utilities down the middle. She started dating a guy about 6 months ago, and since then, he has spent maybe one night per week at his own place. He eats all his meals here (they buy their own food), all his laundry is done here (by her), and to my knowledge, showers here regularly.

At first, it was very irritating because he was here when I woke up and here when I went to bed. And not in her room; out lounging around like he lives here. I’ve since talked to her and asked when he was going to start paying some rent. She refused to ask him to do so stating that if he paid rent, he would have his friends over all the time and she’s sure I wouldn’t want that. Since then, she has basically tried to hide the fact that he lives here from me.

At this point, I rarely see him (or her for that matter) because our work schedules differ and because I feel like she’s sneaking him in and out. But, it still bothers me that this guy basically lives here and doesn’t contribute to the rent. He is out of my way, not eating my food, is polite… but I still feel jipped.

Should I be letting this bother me? Should I let it go? Should I bring it up again or should I keep my mouth shut? I don’t feel that there’s any compromise with her.

Edit: This is a 29 year old woman and a 23 year old kid whom she claims to not care about as any more than a good lay…