You can't force someone to do something they just don't want or like to do. If all other sexual activities are satisfying, just count your blessings and make do without.
Do WHATEV it takes to improve it for her, even if it means a subpar BJ: do it in the shower, de-hair, put a time & frequency cap on it, don't come in her mouth, change your diet, etc.
If BJs are essential to your sexual satisfaction, and it sounds like they are, then you have to accept that you're just not sexually compatible and end it.
