I did it. I never have been the relationship type (fool around with a girl, enjoy that aslong as it lasts, if I can fool around with multiple girls at a time whatever)
I was in a minor dry spat, no action for a while so I hook up with a girl who normally I wouldn't (trivial reasoning why not)
Later on, we're hanging out etc. she knows it was just fooling around, but she wasn't good at the whole FWB thing, the closest she could do to 'flirting' was *Glomp hug no let go nuzzle* (seriously that was her flirting...) anyway I go to another city for a week to have sex with another girl, come back and ask the first girl if she wanted to hook up again. A while after that... I decided "screw it, I'll try this whole 'relationship' thing" so I asked her out, she said yes instantly and now we've been together for about a year and I've grown really attached to her.
(She went from "random person in the background of our social group who i didn't care about" to the person I love.) Our relationship is going good at the moment, the whole 'monogamy' thing is wierd for me even still... but she's bi so I'm happy!
But regardless of all that... Give it a try, see what you think of her, and even then it will take the serious mindset "I want to make this work" or things won't go well. Relax through it, find out more about her teach her more about you, get a good even balance going with things. Work through any hassles and try to avoid the "screw this it's too much effort" thought, because in the end it really is worth it.