I suggest Lothario defined by Wikipedia defined by as an unscrupulous seducer of women.
It's from the name of such a character in Nicholas Rowe's 1703 tragedy The Fair Penitent
dictionary.com adds the definitions rake, libertine and synonyms Romeo, Don Juan, Casanova.
The Office Romeo is a well-worn term, but I don't often hear Romeo on its own.
To my ear, Don Juan and Casanova have become rather quaint 'literary' clichés much overused by the mass-media, but somehow Lothario still seems to have a certain freshness. Maybe using it gives the impression you're well-read, rather than getting all your words from popular tv dramas.