Specific word for man who has an ungentlemanly attitude towards a romantic partner

I'm trying to remember a very specific (old-fashioned but not completely uncommon term) for a man who behaves in an ungentlemanly way towards a romantic partner --for example, a young man who boasts crudely to his friends about his liaison with a young woman who had asked him to keep it a secret.

The word is not lout or churl or chauvinist. The connotations are of someone who is ungrateful and immature --someone who is unappreciative of the sexual favors they are receiving.

Sample Sentence: I didn't mean to be a _____ when I insulted the breakfast you brought me in bed this morning.

If you're looking for old-fashioned, the first thing that springs to mind is cad.

a man who acts with deliberate disregard for another's feelings or rights

Merriam-Webster

The Google definition backs this up as an appropriate answer:

a man who behaves dishonourably, especially towards a woman.

as you did specify the behaviour would be towards a romantic partner, and this fits well.

I think you may be looking for the word cad.

a man who behaves dishonorably or irresponsibly toward women.

The word has broader meanings, but my experience is that the specific meaning you seek is its usual meaning.

Synonyms here.

Of course, if a man is not a cad, sex with a woman is not merely a favor that she does him.