astarte952 said: what will she do if the choosen man is married or not live anymore in the village? i have never heard that snow womans steal man from married womans.
As far as I can tell, the Law of Dramatic Narrative says that the guy would only be boyfriend/girlfriend at the time that she comes back. (Or maybe she'll stalk the guy in the meantime, and meddle secretly, or if desperate, openly to prevent the guy from getting married to anyone else.) That way, there can be some Love Triangle action before the whole thing gets resolved.
If not, I guess it depends on the Yuki-Onna... The really poisonous type may just Murder the Hypotinuse, and "reappear in his life" to "comfort her grieving love". The more honorable type may just wish her former love well, and seek a new soulmate. The more lascivious type might just try to convince the guy to take her up as a mistress and just share the guy with the other girl, although that seems like it would be rare, considering the personality type of this particular type of monster.