This one is really depressing, so read at your own risk. If you want less depressing headcanons, they are here.
Tara was a lieutenant and Ronin was already general when Tara became queen. They already had a serious relationship when it happened, although they weren’t quite to the point of talking about marriage.
When Tara was coronated, the progression of their relationship came to a very abrupt halt, not because of Ronin, but because of Tara. The scope and magnitude of what being queen required meant that Tara was not free to commit herself to anything or anyone else. Her life became about serving her people.
They never talked about it. It was just understood between them that this was how it had to be while Tara was queen. They dealt with this in different ways; Tara teased all the time, and Ronin tired to maintain control of himself all the time.
They also never talked about what would happen after Tara’s service as queen was over, because they were both afraid to jinx it. Chances are though, they would have had a very quick engagement and a very long marriage.
So Ronin waited a hundred years for Tara, then lost her just when he almost had her.
If you now need cuddles, itty bitty Nod gets cuddled a lot in the Feral Nod AU.