That is hilarious because I love to drink milk with sweet pastries and my girlfriend also thinks drinking straight milk is disgusting. It's hard to explain why, but I think the main reason is that I am not super into sweets and milk seems to counteract the sweetness. I also get heartburn frequently and milk tends to help my stomach not feel terrible like it would if I ate a sweet pastry by itself.

At least that's better than drinking buttermilk and a cheese sandwich :)