Dude, it's a mental thing. Some women DON'T swallow. It may or may not have a little to do with the taste, the consistency, etc. but the majority of the obstacle (for you) is in her mind. I've had all permutations of girlfriend when it comes to this question. Some will suck, let you come in their mouths, then spit. Some suck like there's no tomorrow, then when it's time to cum, they stand back and let it fly. Some will suck, lick and swallow with abandon. Some don't even want your cock near their faces. Count yourself she blows you at all!

Seriously, do you eat her? If yes, do you tell her how good she tastes and how turned on it would make you if she swallowed your cum? Tell her these things in the heat of passion, she might be more receptive to them if she's already turned on.

Whatever you do, don't force her. If she doesn't want to, she doesn't want to. You might just have to find someone else to swallow if that's what you really want.

__________________
"Even a man who is pure of heart
And says his prayers by night
Can become a wolf when the wolfbane blooms
And the moon is full and bright."