Tennant's boyfriend staying for free- what can I do?

[Jim Stanley]

I am renting a 5 bedroom SFR in Highlands Ranch (suburb south of Denver) to 3 young ladies who just graduated from college and are all starting to work at a prestigious aerospace company in town. All three have excellent credit, etc and the company only hires the best, so I felt good about renting to them. But one of them has a boyfriend who sleeps over a lot (maybe every night- I'm not sure ) and he's not on the lease. If he is truly living there, I would be happy to put him on the lease and get some money out of him. I did ask him where he is living and he claimed he is renting a house nearby with a couple of other guys. He is here working for the same company as a summer intern so he will be out in about 2 months one way or another.

It's not a big deal, but I don't like feeling taken advantage of.

The lease is the standard Colorado lease I got here on BP as a pro member.

Thanks