As we all are Real Estate Agents, and NOT attorneys, We may only make suggestions.
1.For any type of "partnership" it is best to contact an Attorney that specializes in Family Law to draw up a contract that spells everything out about your partnership/potential marriage, what each individual brings to the relationship and their endeavors, spell out the "What ifs" situations that may occur in life.
2. The Title/Deed would have the names of those individuals who hold the mortgage when purchased and first Closed. You may ask the Title Company what is the best way to put your name(s) on the Title.
I hope this information is helpful1 Would be happy to assist you with finding your new Home together!