Deirdre and Sigurd falling in love instantly comes to mind...
Your point here though, probably shouldn't be "FE has shitty writing" but "People worship certain characters and yell at anyone who dares disagree". Fates had bad writing but I'll have to disagree on 3H having it, and I'll ask you what is "well written"? Well written is kind of subjective, not entirely. And to back up my claim, I consider a story well written when it makes me care about the characters and enjoy their interactions, not the only factor but a big one for me. Fates failed at this. To a lesser extent, if a story can surprise me with a twist it's not a bad story. 3H did this with "Jesus Christ the Pope is a dragon get in the car!" Loved it.