From California:
I am currently dating a girl, and she is living with a roommate in an apartment off-campus (UCSB). Both of their names are on the lease, they pay equal rent, and the lease says nothing about having guests over or spending the night. They also never wrote up a written agreement about anything.
I had spent the night with my girlfriend occassionaly (perhaps between 6-10 times over a 2-3 month period, non consecutive). I visit my girlfriend often usually at night at about 8pm and then i stay till about 11pm-1pm. We stay in my girlfriends room 90% of the time. When we leave the room it is to go into the kitchen or bathroom, never into the other roommates "room" (her bed/stuff is in the living room).
Her roommate goes to sleep very early most nights (9pm).
Anyways apparently she (the roommate) was unhappy with me staying over occasionally, being over in general, using the bathroom, etc. She never said anything about it, but over spring break she complained to her dad who wrote an e-mail (on sunday March 30th, 2008) to my girlfriend saying she was violating the lease and california tenants law (or something vague like that), that everything he demanded (that when his daughter went to sleep the kitchen shouldn't be used and all noise needs to stop, etc.) must be adhered to or that he would go to the landlord and report the situation and that there would be all these consequences and that my girlfriend would possibly be evicted/fined. The e-mail had a very threating tone and upset both my girlfriend and her mother. The father of my girlfriends roommate, in the letter, tried to portray me as a "non-paying boarder" and that i was "living there", even though at best what i was doing was sleeping over occasionally. Also, the roommate had her friends over late frequently, and also had friends sleep over frequently.
Anyways, my girlfriend decided to move out because in that e-mail the father stated he would pay the remaining rent for the rest of the duration of the lease. My girlfriend found a new place and will be moving in there this Sunday April 6th, 2008. In the course of the week in between, i have still been coming over to see my girlfriend, though less frequently, and not staying over at all. Now the roommates father is going to his lawyer and possibly threatening my girlfriend with a lawsuit because i have not abided by all his demands in that e-mail, which was not a mutual agreement between the two roommates.
Have we done anything illegal? Does her father have any kind of case against us? It is essentially his daughters word against ours, and she has for a fact exaggerated the claims she made to her father greatly, as reflected in his initial e-mail to my girlfriend. She is upset because she is already stressed out enough with work and school and the threat of a lawsuit/legal action is not helping. Plus she doesn't want to have to have her family incur hefty legal fees from a lawyer, especially if it is not necessary.
Thank you!!

