Just thought something up, as an exercise in making custom moves:
When you find your beloved (no one said “betrothed”) you choose a power of your love: 3 – true love of all your life, 2 – strong, powerful love, 1 – maybe love, maybe just warm feelings, 0 – a one night stand, really.
When you come up on the bed with your beloved (be it man or woman), roll+love. On a 10+, you give your beloved an oath or a gift as a sign or a promise that you’ll live to be 100, or you don’t make promises but you both feel that you’ll die well in advanced age. On 7-9, you give your beloved an oath or a gift as a sign or a promise that you’ll live long and die well in advanced age, or you don’t make promises but you both feel that you have more to do before you die. On a miss in any case you will yet survive this.