I’d been equally foolish for feeling a shred of pity […] for someone I had so stupidly thought would really care if he met someone who perhaps felt the same, perhaps understood–in my ignorant, insignificant human way–what it was like to bear the weight of caring for someone else. [I] should’ve known better than to think that maybe–maybe there would be someone, human or faerie or whatever, who could understand what my life–what I– had become these past few years.
Feyre’s reflection on Tamlin in Chapter 13 of A Court of Thorns and Roses, by Sarah J. Maas.
Notice how she highlights her longing for someone who understands what it was like to bear the weight of giving herself up for years in order to care for her family.
Sure, in the end, Tamlin does reflect some of that because of how he suffers Amarantha’s curse for his kingdom, but it wasn’t entirely devotion for his kingdom, was it?
You know who does fulfil these aspects? Rhysand. Even before she met him, Feyre already longed for someone like him. He gave himself up for ages, allowed everyone to hate him, just to protect Velaris and his Inner Circle.
From the beginning, she had been looking for someone who could understand her sacrifice and her undoing. And he needed someone like that just as much, if not more.
That’s one of the many reasons why they are perfectly matched.