I always knew they'd put Dany and Jon together

It's the obvious way for Dany to win back the North, which is wanting to break off and go its own way. They wouldn't easily submit to conquest, but they'd follow the king they chose, if he made alliance with Dany, which looks likely.

That said, I think Jon's a good influence on Dany. Dany is proud and willful, which occasionally leads her to excess. She can be both imperious and peremtory, making final decisions and discounting her advisors' advice. The argument over the best way to deal with the Tarlys was just the latest example. Not only does she have the mad king legacy, another problem is, she was without a good role model growing up. All she had was a stupid, arrogant, spoiled, entitled older brother. Actually, given her upbringing, it's impressive she's as morally centered as she is.

Jon, on the other hand, had the best of fathers as a role model (morally at least) -- a man who instilled in him a profound sense of duty and honor. Ned Stark taught Jon to do the right thing, no matter the consequences to himself. It was clear from the last episode that Dany is falling for Jon largely because she sees in him the precisely the kind of leader she wishes to be herself. Jon is a man who will bear any burden, undertake any risk, make any sacrifice, up to and including his own life, in order to serve and protect his people. He's a ruler who views his position as a duty to be fulfilled, not a privilege to be exploited. He puts the good of his people above his own safety and welfare. When Dany saw all the scars from all the wounds he's taken, and clearly was remembering Davos' statement that Jon had taken a knife in the heart for his people, it was obvious she was realizing this.

So for all her irritation at "heroes" who foolishly risk their lives to outdo each other bravery, it's clear that she actually is falling for John because she admires the hell out of him, and realizes he's not someone who is acting out of bravado or simple competitiveness, but rather out of a deep sense of obligation and necessity. In short, he's not only brave, but the most selfless man she's ever met, and she's going pretty gooey over it.