tell her a fact only a future you would know.
like how she is a yandere or how she plans to kill you if you leave
i literally roleplayed like i was in a time loop, proved it to the girlfriend by calling her out as a yandere, explaining what happened in each time loop.. first one she killed me, second i escaped, third we became a couple, fourth we became a couple for a longer time, and fifth was the current. in the fourth timeline the world ended after 7 days, ending the time loop. in the fifth time loop i convinced her i was in a time loop, said it was ok her being a yandere, hugged and cried in her arms about my situation, talked about whether herself in future loops are the same, (she said her core was the same) complimented her telling her her core was bright and hot like the sun, told her i at least wanted to get rid of my virginity, roleplayed 6 whole days in the game getting to know eachother, LITERALLY had sex with the girlfriend on the 7th day, and the apocalypse came and we died together. i then quit the game.