I used to have a house mate who was quite loose. Every Friday night she would pick up a different bloke at the pub. She would also frequently go into depression mode where she would bawl her eyes out for hours.

First time I came back from work finding her nude in the kitchen crying it freaked me the fuck out. By the third time, could not care less.

I first noticed it with her, the monthly birth control/anti depressant combo. Seen it a few times since.