Comedic body paragraphs entail the disastrous event that was so funny. It goes without saying that it should include detail, humor, and your personal flare. A comedic fiction isn't something that everyone else might find funny, it's something that YOU find funny, therefore you should have some of your own flare into the paragraphs, more so than usual. If you aren't laughing at it, then you're not doing it right. Because the only right way is if YOU are having fun.
Fluff body paragraphs are all about the softness of the character and the happiness in the moment, whether or not it's sweet or bittersweet. If it's just sweet then go ham! Make it as sappy as you want, make me want to eat some salt because my mouth tastes like syrup and I'm smiling too much. If it's bittersweet be sure to include more of the event/thought that's haunting the characters. Fluff is soft, you've got to have a little bit of floof to call it fluff!
Angst should have a build-up, where the character is hiding their emotions, it makes for a better explosion of pain and sorrow where they throw their words about how angry and upset they were. Of course, you aren't limited to this, instead, you could just make it where it's obvious they're upset but unwilling to admit that they're not feeling good. There are two ways angst generally goes and I'll specify how the body paragraphs should be laid out.
RESOLVED
These chapters/paragraphs should have negative emotions with a repetitive wish that they would stop feeling it if only to help better the other characters involved. They want to live still but feel like they shouldn't, and don't deserve the other character's affection. The other characters show affection to them, and the main character fakes happiness but still doesn't believe that they're being truthful, and most likely believes they pity them. The big event related to the biggest arc of angst has already happened and has narratively been dealt with. Now comes the side effects and the other angst arcs. Sorry little meow meow I must put you through things once more.
UNRESOLVED
These chapters/paragraphs should have negative emotions with a minor wish they would stop feeling the pain, deeming that ending their life would make everything better for everyone around them. The people love the character but are distracted by something so they can't show it, leading to them spiraling even further into actually doing something. They either kill themselves, leaving the other characters devastated (or unaffected depending on how cruel you want to be) OR they leave abruptly, finally telling the other characters how they feel and leaving without letting them speak. The biggest angst arc is occuring and it is very distressing to the character and aimed to be distressing towards the reader.
Romance chapters/paragraphs depend on the type of romance you're writing.
PINING
These chapters/paragraphs should include the character thinking of the other, finding more and more things about them attractive. Getting closer and closer to initiating a relationship but always convincing themselves not to at the last moment, instead watching the other leave and wishing they'd admitted their feelings. It should be about the characters and how they interact, flirting with each other and maybe the other oblivious or panicking and not knowing how to respond. Of course, maybe the character you're writing for has a different style of pining. Maybe they're just a silly guy who can't shut the fuck up and end up spilling the beans and instead, these chapters/paragraphs could be the character immediately avoiding the shit out of the other character[s].
ESTABLISHED
This should be about the big moment. You can make it about an event with a subtopic of a fight, or vice versa. Personally, I prefer my relationships to have a little bit of hurt/comfort. Some angst sprinkled on top of that fluffy sundae of sweetness. But pure fluff is fine. To me, it feels forced and I don't feel engaged without a little conflict, but guess what? You're the writer, if you want to write pure fluff, do it!!! Some people like to read pure fluff! But if you don't like to write it that way, but somehow find yourself always ending with that I'd recommend putting a minor roadblock to bring something new and cause a little conflict. Bring the room down before telling a funny joke, y'know?
PROBLEMATIC
This kind of relationship in works tends to be shorter by nature due to the fact that they tend to be almost pure conflict with no fillers. First of all, if you want to make it longer, put filler! Put in a scene with a friend who's concerned or just having a silly time or doesn't notice what's going on! Make that character go to a party they don't want to only to be abandoned by their partner and end up self-reflecting while getting only a little drunk! Give them a dream sequence! Put them through normal life scenarios when they're not having a (not so) silly time with their partner! Problematic relationships can be about several things, sinking ships, toxic behavior, or just people who cannot move on from trauma or communicate, and therefore body paragraphs/chapters will vary wildly. Toxic body paragraphs/chapters should (in my opinion) be drawn out, at first it isn't obvious that the relationship isn't healthy, or at least the character can't tell, and then slowly introduce more red flags until the character is drowning. Maybe give them a few of their own red flags. Sinking ships can have just the most miserable sequence of both characters being upset, or just one while the other tries very very hard to make things work or chooses to watch it sink. Trauma issues and poor communication skills can have something minor turn into a big deal because who needs to talk when you can just assume the worst and lash out? The worst game of telephone perhaps.