Haste life-shortening if unaffected

A Sword of Life Stealing gives you temporary HP every time you make a critical hit. If you or your allies have Raging Song, Bloodsong also gives you temp HP on a crit, while under its effects. If you can add Lifesurge, it adds more temp HP equal to the weapon's bonus, every time you gain them from another source.

For "real" HP, a Vampiric weapon will give you up to 12 HP per hit, but only 3 times a day.

This is a matter of story and should be treated like one.

The answer here is not to dig through books to find something like this. It’s to discuss your character’s goals withe the GM and state that your character if always on the lookout for things that might be able to grant this boon. Make the quest to get it part of the game. There could be long-lost relics, gods willing to offer it for completing some quests, or other options. Just like you wouldn’t look to find how to get revenge on the man who slaughtered your village in a sourcebook, you shouldn’t expect a sourcebook to answer this dilemma.

The problems with digging through books are twofold.

1. You probably won't find exactly what you’re looking for, you’ll probably find immortality, which means now the elf has the same problem you currently have. In 3.5 there actually was a prestige class that gave elf-like longevity to other races (ruathar, Races of the Wild), but that is not in Pathfinder. You could try to reincarnate into an elf, but that is really awkward—and not necessarily what your character really wants.

2. This is more systematic—the game’s rules only have one way to make something special: they have to make you pay for it. Immortality should be special (or else everyone would have it), so the game makes you pay quite a lot for it. But there is a mismatch between what you’re paying (metagame character-building resources, such as feats, levels, or whatever) and what you are getting (in-character narrative benefits, which in this case have zero metagame value).

   The GM can handle this situation vastly better than a rulebook can, because the GM controls the entire world—and thus can require you to do things in-character, via the narrative, in order to get those narrative benefits. And he can and should do so without making you expend metagame character-building resources for it, because it has no metagame character-building value. It’s story, not character building.

This problem is actually remarkably similar to the problems with the Leadership feat (though that is definitely not at risk of being wasted resources; in that case, it is often overpowered). Leadership should be built up through roleplaying and narrative; you should have a cohort and followers because you are someone people want to follow and so on, not just because you took a feat. Likewise, you should have something rare and special like immortality because of some grand quest, not because you took a feat, mythic power, or class feature.

Because that kind of mechanistic approach just isn’t satisfying unless it gets worked into the story anyway. “I hit \$X\$th level, now I have immortality babe, we can spend eternity together now!” just kind of falls flat. Obviously you could (and should) do more to make it part of the story, but if you are doing that anyway, why bother digging through books?