dapper-dog 

A dapper-dog is a man who is polite, chivalrous and attentive during the initial stages of dating until he has sex with a woman (or man if he is gay). Once he acquires sex, the thrill is over and he no longer feels the need to wear the mask of a dapper man and resorts to being quite rude and distant.

Tina was surprised when she did not hear from her boyfriend the next day. She assumed when she did not hear from him at all that she had initially misjudged him and that he was a dapper-dog masquerading as a gentleman.

dapper-dog by Narcbuster May 31, 2018