I purchased a home in Nevada, my name only appears on title and on the mortgage loan. I live with my significant other who pays 50%

The plan to put in place depends on the contingency against which you want to protect yourself.  If you are planning for transfer of title upon your death, estate planning techniques (will/trust) can protect you/him and ensure that title to the property passes in accordance with your wishes. If you are planning for what would happen should the relationship end to ensure that he does not make an adverse claim against your ownership, you should memorialize your economic relationship through a lease or other agreement that reflects that his payment equal to 50% of the mortgage is intended exclusively to pay for occupancy of the residence for a given month and does not convey any legal or equitable interest in the property to him.