Your character needs a clear obtainable goal. Staying abstinent indefinitely doesn’t promise a conclusion.

Also, the stakes still aren’t that high. What will happen if he sleeps with someone? He’ll feel guilty, go to confession….and that’s it.

What if he falls in love with a girl, but she knows about his reputation, so she says, if you can stay abstinent for 3 months, then I’ll be with you?

Or he has a life changing calling to be a priest, and the bishop says, if you can stay abstinent for 3 months, then I’ll consider you?

You have most of the right elements there: the main character, an obtainable goal, and appropriate stakes. You need to strip the logline down to just these essentials.

Firstly, your hero has two motivations, saving the country, and winning the hand of his childhood sweetheart. Mentioning just one will do. Make sure its the most primal and therefore the most understood. Saving his country is honourable … but can you make it more personal? How about saving his village, where his friends and family all grew up? Or saving his childhood sweetheart? But that’s up to you.

What does this year long tournament involve? Jousting? Are there teams that battle each other? If it is unique, and part of the hook, you should tell us.

You could also include the villain if any, and a character flaw and/or strength.

Here’s my attempt:

To save his village, a disgraced, ::flaw/stregth here:: nobleman must win a popular, year-long, jousting tournament, facing the ::describe unique villain/obstacle here::.

By the way, what do you mean you submitted the logline for comments not the pitch? The logline is part of your pitch. Commenting on your logline is commenting on your pitch.