@liszst
i can think of two likely possibilities:
1. he really tried to woo her every lifetime but she rejected him everytime
2. since he's a fortune teller, maybe he can actually foresee her fate 100% and she's fated to be unhappy
no matter which man she gets, so even if he marries her, she'll somehow still end up unhappy. a possible explanation for this is that she is actually cursed that whomever she loves will end up dying soon, so he decides it's better to keep her away from all men/potential marriages so she doesn't fall in love.