Cana can't remember when it stopped being a joke. She can't place the moment when the flirting became less harmless than originally intended, and the thrum of her blood in her ears turned to relentless roaring whenever Juvia came around. The little touches Juvia bestowed became infinitely more troublesome, because her skin burned wherever their skin made contact.
She hated it. Cana did not fall in love, it just didn't happen. She liked to fuck and to be free to fuck whenever and with whoever she liked. And she was really, really good at that type of life. Mira once told her she had a fear of commitment, and Cana couldn't find any evidence to refute that point. Whatever, Cana liked her life. Her sexuality was one of the few things she had complete control over, and she prided herself on that liked boys and she liked girls, but Juvia was different.
Juvia was uncharted territory. And honestly, that terrified Cana. Juvia was sweet, she was naive and she was in love with one of Cana's closest friends. Which sucked, a lot. Gray was a good guy, and Cana loved him like a brother, and she found herself becoming jealous of him. He attracted Juvia's attention so effortlessly, and he hardly spared the poor girl a glance. Cana couldn't hold a grudge over him, the guy just didn't do romance.
Another thing Cana and Juvia had in common were that they were both chasing unattainable people. So Cana was stuck with drinking at the bar and forlornly watching Juvia across the guild. As long as Mira kept the beer flowing and kept her from saying anything in a drunken stupor, Cana was content with her shit show of a love life.
The worst part of it all was quite possibly the fact that Juvia was completely ignorant to her effect on Cana. Cana was a good actor, and a damned good liar, but even she didn't make a big show of hiding how she felt. Juvia had to notice something was different from the way Cana looked at her. Erza once commented that Cana looked at Juvia "like she hung the moon in the sky just for her", which Cana kind of hated. But she could appreciate the poetic element Erza was trying to convey. The truth was that Cana wanted all that romantic shit, she wanted the bubbly, spooning type of love that Erza and Levy read about in their dirty novels.
Juvia wanted that too, she was blatant about that much. She made it very clear that she wanted Gray in more ways than one. Cana tried not to be jealous of that. Juvia wanted and deserved love, and Cana wouldn't be angry with her if she got it elsewhere. She just really, really wanted Juvia to find that with her.
But Cana was content for now, just sitting at the sidelines, watching Juvia chase after Gray. It made Juvia happy. And if Juvia was happy, Cana supposed she could be as well.