I made peace with Betty Banner's death a while ago. Her death was in 1998 in one of Peter David's final issues on his historic run on the title, and it not only fit with the personal tragedy in his life at the time, but it fit with Bruce Banner's own themes of loss and solitude. The Hulk isn't known for his jet-setting and warm family life after all. After her death, the book went on in a new "Rampaging" direction, and that was that.
Paul Jenkins came along later and, at least for me, squared away some of the lingering hurt and loss from losing such a central character of the book. We had not just the Hulk, but Bruce Banner himself defeating the man/monster who killed Betty in The Incredible Hulk Vol. 2 #50; the battle between the two is barely kept on the physical page by the brutal force of John Romita Jr.'s artwork, and the final moments of Banner walking away from the emotional prison he'd created for Blonsky is just as powerful. Three years later someone pays for Betty's death and a couple issues later, Bruce himself comes to understand that her death is permanent. In The Incredible Hulk Vol. 2 #28, the darkest and most evil part of Banner's personality tries to make a deal with Bruce: He would allow Bruce to live out a dream life with his beautiful wife and kids in exchange for full control over Banner's body and, by extension, the Hulk's. Bruce kisses the image of his wife goodbye, walks away from the deal to accept his fate and weeps for the loss.
That's the issue I finally said goodbye to Betty Banner. The idea of ever getting her back would be a fantasy, some sort of trick because without her, Bruce moves on. With her comes the expectation that he could live happily ever after and, as Editor-in-Chief Joe Quesada loves to remind us, no one would want to read a book about the Well-Adjusted Adventures of Married Man. Or at least a Hulk that's settled down and worries about PTA meetings. If he doesn't get the good life with Betty, then all he's doing is dragging her through one tragedy after another, and if you truly love someone, you'll let them go.
But heaven forbid we ever do that. Real death certainly doesn't equal comic book death, no matter how much readers may tire of the revolving door. Editorial decides death due to character arcs and sales concerns, not for the soul-searching reasons we deal with as people. If done right, death is a setting stone both in the dead character's life and the stories of those around them. Captain Marvel inspired a heck of a lot of people by dying from cancer, the Vision has been torn apart to give weight to "Avengers Disassembled" and returned to give even more weight to Young Avengers. Most importantly, if a death is good enough, they can always do it again.
Starting back at your core-concept Hulk, he's traditionally a solitary character. It's "Leave Hulk Alone," after all, not "Everybody to Hulk's Place to Watch Mad Men." I think this isolationist attitude comes from Bruce Banner rather than his monstrous alter-ego, as self-destructive people can isolate themselves from others. In "Planet Hulk," the perspective of the book changed and we saw a Hulk who, after some reluctance, gathered followers, friends, a wife and a kingdom. The Hulk needs to be the Strongest One There Is, and to do that you need people to be stronger than. Not to mention the fact that anger junkies need something/someone to be angry with. This wasn't Bruce's story any more; it was his ego talking, and what better way is there to express an ego than by ruling a planet?
A world war, of course! The two gamma wars we've had since have toyed with the idea of being alone versus being a leader. The first "World War Hulk" had the Hulk himself in full control as he ran a campaign of vengeance on New York City and the heroes contained therein only to find out the truth of what happened to Sakaar, reverting back to Banner to not only end it all, but isolate himself from those he led here in the first place. In the most recent "World War Hulks," Banner has gathered a small army of friends and family to oppose his Rogue's Gallery, but he's also been notably making deals and plans behind the scenes. He's been keeping his secrets to himself as well as relying on others for help.
Maybe after all this time, this is the result of bringing Banner and the Hulk together, someone who wants to be alone and someone who wants to smash others. Maybe Banner's using people to get what he wants, being the strongest while never letting in anyone as an equal. Even if it's a shot in the dark, someone should be skeptical if they've been through enough with the guy.
Which leads me back to Betty. Despite her rather traditional damsel-in-distress beginnings, she's never sacrificed being her own person. Several times she's had to move on from Bruce because of his inner demons, no matter how much she loved him. She's moved in to a convent, married another man, even enforced a short separation after Bruce permanently became the Hulk. She loved him, but knew better than to get involved with someone down a dark path.
Her death came at a huge turning point for The Incredible Hulk, paving the way for several major storylines since. Without her death, launching the Hulk into space would have turned out a lot differently. General Ross's rage would have been a lot differently focused. Bruce wouldn't have let go of that perfect dream life and come closer to accepting his own.
At the end of Incredible Hulks #612, the Hulk admits that "You knew something was gonna get broken." He's looking at the ring he had saved for years then offered back to Betty a few pages before, now twisted from the fight he'd had with her new She-Hulk side. By the end of this, I don't think it's just the ring or the marriage that will be broken and twisted. Because if a death is done right, they'll do it again.