Hurt the characters you care about, and give the lucky breaks to the characters you hate. If the audience is outraged, good. That means they care.
This. A million times this. For this reason, I just can’t understand why Sera Gamble’s reign as showrunner on Supernatural is so unpopular. I mean, it’s a GOOD THING that she’s making all our favorite characters suffer. That’s what writers are supposed to do to characters you love: Poke them, hurt them, torture them. Give ‘em some meat to chew on; help them grow, learn, evolve—even if that evolution is in a direction that’s uncomfortable or painful. Conflict-less stories where the hero always succeeds and says all the right things and never, ever makes mistakes, I mean, how is any of that interesting at all? Screw that. I say raise the stakes. Make my babies bleed. Feed off my fangirl tears.
And that goes double for shipping. Stability, honesty, unconditional support — all wonderful qualities in a real-life relationship, but what works in real-life doesn’t always work so well on-screen. Stories require conflict to move forward, and that includes stories about love and relationships.
And if you’re a Destiel fan… I mean, c’mon: Season 7 alone is basically all about Dean mooning after his space-boyfrand. From the pain factor alone, I’d think it were obvious that nobody ships these two harder than the damn show itself.
tl;dr version: To writers, pain = love.