First, let me just say that I don't have anything against romances in general. I'm not a huge fan of the genre, but I'm not going to tell an avid romance reader that they're wrong or have bad taste. You read what you want, and I'll read what I want. I've actually read books with great romances and relationships that I liked. And, I've also read some where the romantic subplot was boring, or felt unnecessary or took up too much of the book. Now, I think I can divide my negative opinions about romance and romantic subplots into three categories: overdone, unnecessary and just problematic.
Overdone
I know a lot of people love Romeo and Juliet but I'm not one of them. I'm tired of books being adaptations of the play. Some retellings have been done very well, but there's an over-saturation. I like star-crossed lovers just fine, but star-crossed lovers where one or both have to die in order for the story to stick with you? It's been done to death, and I hate it. If you want your romance to be broken up because there needs to be some type of sacrifice, it doesn't have to be death. Imprisonment, exile, and even plot devices like "if I ever see you again, the world will explode" make the two characters splitting up much more impactful than one or both characters dying.
Also in this category, love triangles. There doesn't need to be one in every YA series. If yo're going to write about Girl Character not being sure if she wants Boy A or Boy B, fine. But the "triangle" can't just be the fact that both boys like her and she doesn't want to choose. Show why she's torn between Boy A and Boy B and why she should and shouldn't chose each one. Also, please don't make Boy A a childhood friend and Boy B a handsome new kid, because we know what's going to happen there. The reason why I don't like love triangles is that, if the book is not categorized as strictly romance, it can rob the story of its impact. For an example, The Hunger Games is about overthrowing an oppressive regime that forces children to fight to the death, but too many people turned it into Peeta vs. Gale.
Unnecessary
As mentioned above, not every story requires a romantic subplot. And, even if there is romance in the story, it doesn't need to be a huge focus. My favorite book on Earth is The Hobbit. There is no romance in The Hobbit because the story doesn't need it. The Harry Potter series has romantic elements sprinkled throughout, but you could cut out, or skip past those scenes, and it doesn't effect the story.
I've read so many books where 2/3 of the way through, I was enjoying the book, and then all of the tension turned from "stop the bad guy", "solve the crime" etc to whether or not two characters would get together and the main plot was shunted to the back. That ruined those books for me. I would also put last minute coupling in this category. If the main conflict has been resolved, and the rest of the book is just Character A and Character B admitting their feelings, I don't really need it. Especially if, prior to the conversation where they admit their feelings, there's been no indication that either character felt anything stronger than friendship for the other.
Problematic
I know a lot of people cringe at the term problematic, but romances that fit in this category make me cringe, which is why I'm using it. Some of these tropes are fine, just not my taste, while others I find very troubling.
First, the "not my taste" ones. I hate the trope of male characters that are jerks to their own love interests. I don't mean ones where they butt heads at first, or don't like each other at the beginning but slowly get closer and dislike turns into friendship and then love, by the way. I mean ones where the guy is a huge jerk, he stays a huge jerk, but his love interest still wants to be with him. Or thinks she can change him. Or knows that he's actually just damaged and that makes him act this way. Not a good romance, actually really toxic and I don't like it. To a lesser extent, this includes the "I was mean to you as a kid because I had a crush on you" plot, because again, that doesn't excuse the behavior. Insta-love is another one that I'm just not a fan of. If I'm going to be invested in a couple, I want to actually see their relationship develop, not just read "he saw her and knew she was the one. The end".
Now, to the romances that I think are very troubling. One: killing off one or both members of the only gay, lesbian or bisexual relationship in the story. If you do that, you brag about how representative your story is, because its not. In a similar vein, if you write a bisexual character and they end up with someone of the opposite gender, that doesn't make them straight, so don't treat it like it does. (Basically, write happy, healthy non-straight relationships, okay?) Two: romanticizing abuse. I shouldn't have to explain this but there are still people who think the Joker and Harley Quinn dynamic is "goals". Emotional abuse, physical abuse, manipulation, its not cute and it's not romantic. Lastly, relationships involving one adult and one character who is not an adult. We have a word for that, and it's not romantic. Some might argue this one saying that "Character A is 15 and Character B is 18-21, its not that bad". No, it is. Because the author chose to make the characters those ages. They could've both been in their 20s, or both been teenagers, but they chose to have one be an adult and one be underage. Maybe it wasn't intended to be predatory, but it easily comes across that way.
Romance when written well adds a layer to the story being told. Sometimes, that simply raises the stakes. In other scenarios, it brings about a form of character growth. The problems arise when romance isn't handle well. If it's shoehorned it, or it distracts from the main story being told, then I take issue with it. As I said earlier, I don't have a problem with romance in general, just it being misused.
