In WikiTree the philosophy is there is only one tree, thus there are no separate trees for a person and their spouse.
I suppose you could enter your data, and not connect yourself with your spouse. If there are no other connections between you and your spouse, then you would have a separate tree.
If you are keeping data with a genealogy program on your computer, you could create one file for your family, and another one for your spouse’s family. Since they are not connected, you have separate trees.
However, with the ability of genealogy software to handle large data files, there is no need to do this.