LOYAL ENEMIES: A slick grifter uses his sexuality to convince a wealthy, lonely socialite to back him in a high stakes poker game. He soon finds the deck stacked against him.

An ageing gigolo con man who plays a naive socialite to finance his last chance at the big shot has been done to death. Spoiler Alert: It never ends well for him.

One of my favourite movie about a chancer who uses his roguish charm to climb the social ladder, before falling in love with his target and ending up rejected is?Barry Lyndon. That movie was superb for his time. The soundtrack is really the thing that transform that movie into a great melancholic tragedy.

Anyway, personally I would flip the script. Make the naive socialite the main character. She is new and introduced to a world of shark. Will she sink or swim? Her "loss of innocence" journey seems to have more mileage. A good movie on that very theme is?House of Games,?a well known David Mamet movie.
It flips the script in the sense that the initially naive psychologist finally reveals herself to be a thrill seeking sociopath.

>>>?He soon finds the deck stacked against him.

As if we should care? The logline gives us no reason to root for him or even be curious to see if he can win.

The logline is mostly?set-up not story.

Who is opposing the lead character, what specifically is standing in his way?

What are the stakes? What personal thing will the lead character lose if he doesn't succeed?

What situation is motivating the lead character? Why does the lead character 'need' to win this tournament?

This is all missing from your logline.