I didn't enjoy Feylin; from the beginning it seemed stereotypically fairytale & (gradually) so unhealthy. Feysand def pulled me more into the story on the whole. I do think both relationships were vital for every character involved, though. I think Feyre needed the experiences she had w Tamlin just as much as she needed to find Rhysand & finally step into a relationship that was healthy & loving. I'm also supremely relieved that Maas didn't just offer up a bandaid for Feylin but that you do see a lot of growth for both Feyre & Tamlin bc of how things went between the two of them. It's a slower process for Tamlin but you do see that he has some good there when his anger & ignorance stop eclipsing it. I think it's just a matter of him needing someone to stoke that for him; he was too naive and entrenched in his own person to really see Feyre as anything more than a possession that was his to mold.