Shipping. It's a subject that comes standard to every fandom. Even in the most unlikely fandoms, even if there doesn't seem to be any canonical support, you'll get Care Bears BDSM and Pong slash, Hogwarts/Giant Squid and various fandoms that leave you wondering how the heck the characters are making out despite the lack of lips.
At first glance, Disney Fairies is simpler than some -- the characters are at least humanoid and have defined genders. But it's still rather tricky to work out relationships.
Within canon, the only times that reference is made to romantic implications are Rosetta fretting about having a date to a dance, Thistle and Jerome in the graphic novels, and, of course, Terrence's crush on Tink.
Being as the only way that new fairies come into being is through a child's laugh, reproduction isn't in any way a factor in relationships, and thus fairy society would lack any form of pressure to pair off. This isn't to say attraction isn't possible, simply that it would be less common.
Which brings me to my theory on same-sex couples. Being as fairies have no parents, no familial bonds outside the rare case of 'siblings' coming from the same laugh, no version of marriage, no form of religion, and no pressure to reproduce, I theorize that if two fairies -- or two sparrowmen -- became interested in each other, it wouldn't be considered any more odd than Terrence's attraction to Tink.
This attraction did draw quite a bit of attention -- largely in the form of good-natured ribbing from his fellow dust talents. So my theory goes, a same-gender couple would likely be found odd for being a couple moreso than the genders involved.
We know that fairies can express affection through hugs, hand-holding, and kisses (for why else would Tink be jealous of Wendy wanting to kiss Peter), but anything further is rather a grey area. How far a couple might go is up to the author, I suppose -- not all sexual acts are reproductive, after all -- but the fact remains that fairies wouldn't be driven by the same hormonal urges as humans.
To conclude, I'll offer you a quote from Barrie:
After a time he fell asleep, and some unsteady fairies had to climb over him on their way home from an orgy. Any of the other boys obstructing the fairy path at night they would have mischiefed, but they just tweaked Peter's nose and passed on.
Interpret as you will.