I want a divorce! What's the most painless way of obtaining one?

From UESP wiki, "Skyrim - Marriage" article:

Steps to re-marry / divorce using console commands (PC only):

• Select spouse.
• Enter the following console commands:
• removefac 51596
• player.removefac C6472
• resetquest 74793
• resetquest 21382
• setstage 74793 10
• Wait for 24 hours.
• Then proceed to marry as normal.

From TES Wiki, "Marriage - Divorce (PC)" article:

Trying to breakup with partners is, for some reason, impossible without the console. Searching for help "breakup" 4 will bring up dialogue and quests that show reference to what must have been the original intention of breaking up with a spouse.

Option one

The relationshipbreakup quest can be used. Use the console to enter these commands:

• completequest 0007431B
• resetquest 0007431B
• resetquest 00021382

(This is just formality to reset the "marriage" quest.) The above will prevent the player from having to kill his spouse, although they will comment on how much even the thought of him makes their blood boil. Untested, but possibly setrelationshiprank player 4 can fix this

Option two

• The spouse must be killed
• The console command Setstage RelationshipMarriage 10 must then be used
• The console commands resurrect should next be used on the ex-spouse (and eventually the command setrelationshiprank player 4 on him/her to keep the relationship status obtained with the NPC related quests)
• The old Amulet of Mara doesn't need to be dropped or sold.

Option three

• The Amulet of Mara necklace must be retained, or another one must be found.
• Any wanted items should be taken from the current spouse before starting this process.
• The following commands must be used, after targeting the spouse:
  • removefac 51596
  • player.removefac C6472
  • resetquest 74793
  • resetquest 21382
  • setstage 74793 10
• The old spouse will immediately exit the house and return to their regular location.
• 24 hours must be waited.

I'm afraid that it's off with her head, mate.

It's that, a console hack or a mod (not sure if one exists though).