Alright, here’s how it goes. You grow a beard, put on a wedding ring, and then get a tan. Then cut up your back, take off the ring, and your cloths, and pass out in her house. When she finds you you tell her you are from a post apocalyptic future, and have succeeded in going back in time to see her once more. She’ll see the ring tan and you tell her you are married in the future. Then try to kiss her. With the combined nakedness, vulnerability, the kiss and the lie, she’ll have sex with you. Then shave off the beard, cover up the ring tan line, and pretend you are your present self. With any luck she will fall in love with you, which will result in more sex. Or you are over come with guilt, and kill yourself.