Theory: he sent her back in time to undo something that would've happened in the previous timeline, and since this current version of him is aware of the spell being cast but not necessarily the target/catalyst, he's had to look for the person his other self cast the spell on... to stave off the future he cast the spell to prevent in the first place?
No idea if that's how it plays out, but it makes sense from what we've gotten. If that's the case, he's likely to be more of an ally or mentor rather than a potential romantic interest.