Kinda got distracted here but. Short version: the fe13 & fe14 support system is designed as such that it's actively working against the writing, which, paired with fe14's preexisting issues, leads to disastrous results.
For those unfamiliar, Fire Emblem Awakening (fe13) & Fire Emblem Fates (fe14) both have what is referred to as Supports, which is basically a speedrun dating sim: when two units fight together a set amount of times, their affection goes up. As they grow closer, you can unlock three bonus conversation between these two characters, and, if these two characters form a male-female pair*, they can have a fourth conversation where they confess their undying love to each other and get married.
(* Two exceptions to that rule: one, there are two character options in fe14 that your self insert can romance regardless of gender. Two, direct blood siblings** can't romance each other.)
(** Now might be a good point to mention that fe14 in particular features romance options between adopted siblings & blood-related cousins, so like, might wanna hit J and skip that whole post if that's a trigger to you.)
Anyway. The support system! Sounds neat, right? Now you can pair your faves together! Innit cute?
Of course, the intro to this post is literally me saying it's terrible, so you know I'm gonna immediately point out the holes in the concept. So, without further addue!
Problem 1: It is very hard to get anyone invested in a relationship, yet alone a romance, in 3-4 short conversations.
Writing any kind of relationships is hard, because you need to get the reader to not only care about these two bitches hanging together, but also care about said bitches on an individual level; that means introducing characters, getting the reader attached to them, and then getting the reader attached to them as a set. It's hard! And 3-4 convs? That's fast.
Some characters manage to get around that by actually being plot relevant, so you actually get to know them and see how they interact with each other and the world they live in. (There is a reason why Chrobin is such a universally liked ship.) But most background characters, their entire characterisation lay in their introduction scene in the main plot, and then these supports.
That's not saying it's impossible, mind you. Henry & Maribelle's support does a great job showcasing who Henry and Maribelle both are as characters, and what their main dynamic is (aka "homeboy you're out of your mind, but so am I for being into it.") But it definitely make things difficult. There is no time for slow buildup. For some characters, it means showing a glimpse of what a full story about them could be, just enough to let people imagine the rest on their own. For others, it means 20 mins of dialogue on pie-making. (Which, granted, is pretty cute and features some cool characterisation bits here and there, but it's not exactly a conversation that leaves me yearning to see how it'll end.)
A romance system that fails at the romance kinda suck, y'all would agree.
Problem 2: the S supports are optional, so the three conversations prior to that have to be able to stand on their own.
Meaning: each character can only romance one other character. What if your player decided to romance a character, but still unlock the first three supports for another character? You can't be too obvious that these routes are meant to lead to romance, else they'd look pretty shunted!
Most supports actually get around that easily, because they follow the friends-to-lovers pipeline (or enemies-to-lovers pipeline.) But that also means that the few times they try to get funky in their supports, they write themselves in a corner. This is how you can end with three conversations of Mozu running away from Azama, until he confesses his love because?? idk he's into that I guess.
Or. Y'know. All the "of course we're your siblings and we love you as such :)" [two minutes later] "ok so actually-" supports.
Problem 3: the supports are optional, so they can't have any meaningful impact on the story.
Technically, you can speedrun the whole game without checking a single support. Hell, in my first playthrough of awakening, I barely unlocked the first conv for these lads when I reached the end, and I had to sit down and grind my team like crazy to get these bitches married. Which means the supports have to be written as completely disconnected from the main plot.
Now, that would normally be okay, but it can lead to absolutely surreal moments when people's personal relationships, or the shit you learn in these supports, just... don't come up. If you marry Azura, and later learn in the main plot that she's your blood cousin, no one comments on it. Azura doesn't care. Your character doesn't care. No one cares. Hell, if you romance the Hoshido siblings, the pull out a surprise "actually we're not related" card, which is never adressed in the main plot either. This is a major spoiler for your character's backstory and you just... never investigate the implications of that statement. There's also this Kaze/Protag support, where Kaze tells you you remind him of your mother... even in the route where you betray said mother's country and are actively trying to kill her kids.
Had to cut that post short cuz I'm gonna conk the fuck out, but, tl;dr: the way the support system is designed is not only terrible as a romance system (due to providing way too little material for anything substancial + trying to commit to an all-romance system even with characters that aren't compatible,) but it also sabotages the main plot by introducing too many variables (who romances who? when? who knows which info they should really be acting upon?) that cannot possibly be taken into account all at once, leading to blatant contradictions.