Sounds like your mad because Mr. Casanova is getting all the ***** in the office. Raise your game.
He even brought his girlfriend into the office. You say bad, I say shrewd. That makes the girls want him even more.
But he bothers you this much...he's won
exactly. Relax. Why is he getting you so pissed off? You don't seemed threatened. Trust the process, and your gut, and if you know this girl is into you you'll be fucking her in no time. Much better than getting over-aggresive and making yourself very obviously un-attractive. I agree, raise your game, but not in an obvious manner.