And I am offended when people ignore the beauty of a platonic relationship. There is definitely enough subtext to believe in a relationship between the two, but not at all definitive.
Why must two characters be "in love" to love each other? The only answer that makes complete sense from beginning to end of the game is that they are platonic. It's all about context.
Fang refers to Vanille as her "partner": Well, duh! What else would she call her when they are talking about how they were on a mission. Fang is very militant and plain spoken. When she says partner, she doesn't mean "playmate".
Boob grab: It's actually not even a grab, but a placement upon the chest. It's a hug, for goodness sake, and in a video game. Hand placement isn't necessarily going to be 100% accurate.
"I'll tear down the sky if it'll save her...": When one considers what all they have gone through together, being the last of their kind and of their likely non-incestuous family, it's not surprising Fang feels so strongly. I'd go through fire for my best friend, and my love for him is nothing more than platonic.
Basically, you can take it however you want, but the argument for a romance is much less founded than a friendship/familial relationship. /rant