Sleepy Betrayers (1990)

Obnoxious but charming, Paul (Norbert Muzzulini) has lorded it over his roommate and girlfriend Sandra (Annemarie Kneck) for quite some time, flaunting the fact that he sees other women and spouting insufferable philosophical claptrap about the nature of love, etc.. Eventually, the girl (on the advice of friends) turns the tables on him, and claims to have outside relationships of her own. This prompts him to move out in a huff, into the flat of a casual conquest of his, but he soon discovers that his poor manners have resulted in his not being welcome anywhere.