Another one from the Big Bag O' Sexist Cliches.
I didn't want to do "Romantic Stalker Man", so now I have "Clingy Wife"? This is what happens when one tries to think up plots while walking the dog. So, in the last mortal life, the woman (I need a name for her) finds out from a fortune teller (actually one of the disciples of the evil naga) that her husband is about to be called into service by the goddess/die. The wife is pregnant... So, who can blame her if she thinks this would be a bad time to lose her husband? Doesn't their child deserve a father? But she can't talk to him about it, as she feels she can't force him to choose between personal and divine duties. She's going to save him by... making a deal with the naga (who must be imprisoned at this point)!? No, that's not going to end badly at all!
So what was his bad idea? Back in their previous lives, he was late for an important appointment, and on his way there, he saw the woman fighting a demon, but he ignored it and rushed on, even though she clearly needed help. "I'm a gardener, what do I know about demon slaying? Not my problem." Ok, not a sexist cliche this time. Just based on those classic psychology experiments.
So, he owes her a life. Presumably this will be repaid in the third lifetime they're together. It's likely this kind of sacrifice is the only thing that can drag her out of the clutches of the evil evilness of evil. Meanwhile, if they fight, remember that each attack will be returned eventually to the attacker. One stab in the back deserves another. One sacrifice deserves another. If she forgets him, he will forget her. She forgets him because she's lost to the demon. He forgets her because he died and lost his memories.
Oh dear, how many times are we going around this cycle?
And where does the other mission come into it? Plus the subplots with the dog and rat fairies? I'll worry about that later.