is it possible to get married if your spouse is killed(accidentally of course), and does anyone know if either Vex and Sapphire(thieves guild) or Karliah (nightingales) will marry? thanks!

No, no, and no.

You can't remarry just as you can't divorce. And you can't marry thieves (by the way, Karliah already has a lover).

If your wife is killed you can re-marry. Check the IGN website on marriage in Skyrim.

UESP is more reliable and it says they can't unless you have the PC version where you can resurrect them or just remarry.

"If your spouse dies, you will not be able to remarry."

Hmmm, I had seen UESP but never really used it. I recently restarted the game and haven't married yet, the woman I want to marry apparently isn't an option... Kinda bummed.

Maybe they'll add it in a minor patch.

Lol! I stopped playing the game 9 months ago die to bugs and glitches, I started again about 2 weeks ago I doubt they will make many patches that are truly useful. They only care about making new DLC that make them money.

You are bound together in love, now and forever.

Sorry! *wipes tear* I highly doubt it will happen. Especially with the npcs who have unique voices (like Vex and Karliah).

If you're on PC, Sapphire can be married and be a follower with mods. The others can be followers with mods but I don't know about the marriage part.