You can put someone (i.e. spouse) on the house title even if they do not have th mortgage in their name. Its the mortgage that would only be in the persons name who qualified to borrow.

I added my DH to our condo title but my name is in the mortgage since it was bought prior to us being married and living together.

Joint tenancy means one spouse inherits the house.
This can be a problem if the family has his and hers children. So if both are walking down the street and a drive by shooter shoots both, and the wife outlives her man by 3 hours and both are dead. The house is the wifes estate and his kids can do nothing about it