So many people get Rhysand and Feyre’s dynamic wrong.
Rhys and Feyre are mirrors, they both would and have done the “wrong” thing in order to save the ones they love. They both would rather take on the struggle alone then share the burden. They both don’t view themselves as worthy of what they have, and can only truly love themselves when they love each other. It’s why they work so well, they both mirror the other.
When Feyre says “I see you” to Rhys it’s incredibly powerful because she’s not only seeing him but herself. Feyre only begins to forgive herself for what she did UTM by realizing that she could never condemn Rhys for his actions, because she would have done the same.
Rhys hatred of Nesta over Elain, is because Nesta does not appreciate (at least outwardly) everything Feyre did. It’s not just about Feyre providing for the family and them not, it’s about her treatment she got for sacrificing everything. Rhys knows what’s that like, Rhys has done that and knows what it’s like to be insulted for it. And while he doesn’t ever try to defend himself when insulted he can’t bear to see Feyre insulted over her sacrifices.
It’s the same way Feyre cannot comprehend how people can disregard and insult what Rhys did to save his people. Feyre goes ape shit over any insult towards Rhys, but more or less tolerates Nesta’s abusive comments towards her.
It’s because she’s his mirror, and he is hers.
And if we’re think of in canon, despite all the problems and plotholes with the pregnancy it makes sense that Feyre would be quick to forgive. Feyre would do the same, if she knew Rhys was going to die she would do everything to find a cure before he died. It’s not right, but Feyre takes on the burden of others the same way Rhys does. She understands him and his actions better then anyone else. And he understands her equally as well.
It’s why they work so well and what most people get wrong about them. Feyre does not have “rose colored” glass for Rhys, she understands him. She knows she would make similar choices and she has made similar choices.