Talk to the Soldier to receive the letter with the unexpected news.
The winery you need to get to is south and east of Twainbrook. Follow the road south and then east and over the bridge. Keep following until you get past all the trees. The winery will be on your left (east). If you reach the next High Elf Outpost, you have gone past the winery.
Talk to Meliondor and then beat some sense into him. Talk to him again and he will join your party. Before you do this it is a good idea to travel to Thylysium alone and activate the Resurrection Monument there. This can save you a lot of trouble when it comes to getting the suicidal Meliondor to the city in one piece, especially if you haven’t been that way before and done the quest Holdup.
If you run to Thylysium, then head south from the first personal chest in the city until you reach a crossroads (just southeast of the Resurrection Monument and Portal). If you teleport to Thylysium, then head southeast to the same crossroad. Take the east road and enter the second house on your left (north).
Meliondor's sister, the Fiancée is generally on the second floor of the building so head upstairs and talk to her (the stairs are immediately to your right as you walk in) to receive your reward.
Note: If Meliondor dies on the way to Thylysium you can still talk to the Fiancée. She will commit suicide and the quest will be marked as 'failed' in your log.
In earlier versions of the game it is not possible to teleport to active portals from the map. In later versions it is. If you have the portal active in later versions, this feature is enabled. It is a good idea to have the portal in Thylysium active before you take on the task of escorting Meliondor. Watching rats and skeletons chase him around can be quite funny, but he is not easy to keep alive.