I'm selling.my home and putting all.my money into my boyfriend home how do I cover my finacial contribution if anything were to happen to our relation

You and you boyfriend should sign and record a deed naming both of you as tenants in common (having undivided interests in the entire property) or as holding "joint with right of survivorship" (meaning that the survivor inherits the entire propety).  If this cannot be done, loan your boyfriend the money, at interest, with a promissoy note and a recorded mortgage (deed of trust).  If you do neither, you have made a gift.  If the amount is over $15,000, file a Form 709 with your 1040 and pay the tax.  As Shakespeare warned us, "The wont of men was ever so:  one foot on sea and one on shore; to one love faithful never."