How to break off the affair? No problem. If you've read carefully until now, you probably know how. But here's a refresher:
Talk about yourself. Monopolize the conversation.

Contradict them.
When they start talking about their problems or delivering their opinions, yawn.

Forget their birthday, Valentine's Day, the anniversary of the day you met, or the first time you went to bed together. Send a card with a jovial "Better late than never!"
Don't bother to tell them they're wonderful.

Criticize how they dress, what kind of friends they have, how their home or apartment is decorated.

Always let him or her know that your career, your social life, and your sexual satisfaction come first.

Never dress properly. Lounge in your oldest, dirtiest, shabbiest. And don't change when you go out.

If you attend a movie, make it the local third-run and choose the sleaziest sex film. Exclaim over the glamour and excitement of the lovemaking in the film, implying that Leo could learn a good deal from it.

Attack their sexual prowess. Imply that it's all been actually pretty routine.

Deliberately excite their jealousy.
Be thrifty.
Puncture their vanity with ridicule.
Leo will soon be gone, to play King or Queen in some other part of the jungle.