Even if a character is flagged as marriageable, the Radiant AI system may not allow you to marry said character even if you have completed their objective, so it's best to have at least one backup candidate. Is there a mod that makes your spouse go outside and do stuff? These are the goods sold if your spouse was originally an apothecary merchant. Skyrim: 15 Best Marriage, Spouse & Family Mods(Custom Wives & Husbands)

If you haven't yet visited Riften, you can instead pay a horse-drawn carriage outside of Whiterun in the stables or one of the other major cities to take you there. Special care should be taken with chests, as chests may be owned by other members of the house. Note that if your spouse shares ownership of a house with someone else before marriage, other people will be living there after marriage even if you elect to move in with them. Annoyingly the Dunmer is elf-only, and the female NPCs aren't optional. If the person is a hireable follower, you'll likely just need to purchase their services. There are mods, however, that allow re-marriage.

Skyrim best marriage mods