When writing a story, the satisfaction comes from your conflicts being resolved. Now, you'd think this would be a no-brainer, but here's the trick: ALL conflicts have to be resolved, even the man vs. himself conflicts.
So, let's say you're writing an extremely epic adventure romance fic - nearly 200k - and my goodness, you've hooked your audience - your lead characters are sympathetic, your plot is well developed, your romance is romantic.... SO, you've got your antagonist, who is laying in wait to ruin everything, and he's your man vs. man conflict... you've got the environmental hurdles the leads must overcome (ie: they get trapped somewhere and have to escape, or the society they live in stands in the way of their dreams, etc...), and THEN you have the psychology of the hero... this is your man vs. himself conflict... maybe they don't think they're brave enough to get what they want, maybe they don't think he deserves it... maybe, in the case of the fic I just read, they has a really fucked up view of sex.
So, at the end of story, you not only have to overcome the envionment and defeat the antagonist, you also have to address the lead's super f*cked up psychology and make sure that it's evident that they have worked past it - not only that, but you have to make sure there's EVIDENCE that they have moved past it or, at the very least, are well on their way to moving past it.
You can't, for instance, have a main character who has a super fucked up view of sex, and then end the story at the love confession and fade out before anything is ever consummated. Do you want to know why? It's not because you've denied us the smut of the consummation scene. It's because those of use who have been paying attention to your 200k words that constantly reiterate how fucked up this guy is, are going to sit there thinking "okay, but... it's all going to go to shit the first time they're intimate at all" and suddenly that lovely victory you've built up, means pretty much nothing, because you've got this dangling unresolved conflict.
It's like if I wrote a story where our hero is someone who is a giant miserable depressed alcoholic and are likely to die with the next binge drinking event, unless they get help - meanwhile, a serial killer stalks the town, but our hero can't stop them, because there is also a meteor barrelling towards earth, and the murderer is the only one who knows the codes to launch the missles that can destory it.
Now, imagine that's my ridiculous premise - if I have the hero get over their alcoholism, so they can stop the murderer, that's great. But if I ended the story there, you'd be sitting there wondering when that meteor is going to hit... or if I had our hero stop the meteor, recover from alcoholism, but not stop the serial killer - you'd be sitting there equally worried about how many more people are going to be murdered, and why the story ended without defeating the bad guy. Or, if the hero stops the meteor, arrests the murderer, and then I fade out while they're staring at a bottle of whiskey and thinking "time for a drink", you're left not with a happy ending, but with a bittersweet ending where you're like "well... everyone is saved except the hero."
Likewise, if I have a adventure romance, where my main character has a giant personality problem that prevents them from having stable relationships. I can't end the story before I address that problem. I can get rid of as many rivals for their love as I want. I can get rid of all the physical and environmental obstacles that keep our two lovers seperated, but if I don't address the fact that my main character is SUPER fucked up, then nothing is resolved. You don't get a "they lived happily ever after" if there's a 90% chance that as soon as the fic fades to black, the main character is going to have a nervous breakdown.
And addressing the fact that my main character is super fucked up isn't the same as explaining WHY they're fucked up, or having them REALIZE how fucked up they are - I know plenty of people, myself included, who are fucked up, but don't know how to STOP being fucked up. Awareness is not the same as solving the problem. "Oh, there's a giant meteor about to kill all mankind - well, now that we're aware of it, I guess that problem is solved. And we lived happily ever after...." Nope. You all died. This is not a happy ending. This is very much an ending where the reader is sitting there thinking "I read nearly 200k of fic, and you're not even going to RESOLVE THE FUCKING PROBLEM?!"