I've noticed that this subreddit absolutely loathes the idea of Jon and Dany ending up getting married or getting together in any way.
When you look at both the TV Show and the Books, there seem to a ton of hints that this could very well happen.
- The Series is called a A Song of Ice and Fire, where it seems like Jon is representative of Ice and Dany of Fire, them also being the two main characters in the entire series (along with Tyrion).
- In the House of the Undying, the third vision Dany sees in her "bride of fire" is a blue rose growing from the Wall (signifying Jon).
- Additionally, somewhere in ASOS/ADWD I believe there's a passage where Dany reminisces on the deaths of Aegon and Rhaenys, and remarks that she would have likely married Rhaegar's son if he was still alive, as they were closer in age.
- Additionally, in the TV Series, there are a TON of photos that feature Jon Snow and Dany only. See for yourself
Just feel like there's a lot of very strong evidence of them getting together (mostly the House of the Undying Vision), as well as it making a ton of sense (last 2 Targaryens left; the title of the Series), and them being main characters probably also helps, but either this situation is rarely discussed or shot down by posters.
EDIT: I notice that a lot of people point to it being too cliche and a happy-ending as an answer. To that, I respond with this