We met Marion last season briefly, Rumpelstiltskin spared Robin when he learned about her illness, so she's Roland's dad. Interestingly, Tinkerbell's spell suggests that "true love" might be found with more than one person considering Regina's devotion to Daniel (and Robin's to Marion) - I don't think Robin had to "settle" at all.
I could see...
None of those really work though for various reasons; Hook and Rumpel for Milah and Emma/Belle respectively, Pan for the implications, Sydney because obsessing over Regina made him a killer, and other than Grumpy none of the other dwarves matter enough. Basically, although I think they're pulling a Willow with Mulan, it's the best choice barring Henry if you want to reveal one of the main (and not brand-new) characters is gay.
Guy Gardener wrote:
Are fairies sexually mature?
Grumpy seemed to think so.
Although funny you should say that, considering they're nuns in Storybrooke...