It was when everyone was talking about Sophie resembling Grace that I got on the RQ = Grace’s mother kick because I thought Grace looked more like the actress playing RQ rather than the one playing Alice.
A good point but I’m still not convinced. You’re right, “lost” could mean anything but it is the “because of my work” bit that is bothering me. We know Jefferson travelled between realms using his hat, for whatever business that was his work, so why did travelling between realms cause him to lose Grace’s mother? I think Grace’s mother was an innocent and had nothing to do with realm jumping. We know Jefferson gave up realm jumping to raise Grace which suggests that her mother wasn’t around to do it herself. Perhaps someone Jefferson crossed on his travels came seeking revenge and that caused Jefferson to lose Grace’s mother.
One theory I’ve seen discussed a bit is that Grace’s mother was Jefferson’s +1 for hat travelling.
So, take the situation where Jefferson went to get Frankenstein…if he went by himself, then 1 went in, 2 came back, then 2 went back when he took Frankie home and then 1 came back when Jefferson came back home to FTL. Violates the rules of the hat: same number that go in must come back. Therefore, Jefferson had to have a travel buddy to make up the numbers, and maybe that person was Grace’s mother, who came along on the job whenever the +1 would be needed.
This would require Grace’s mother to be sitting around in different worlds, waiting for Jefferson to come back to collect her. So, let’s say one day he had a job in WL and needed the +1, so Grace’s mother is sitting around in WL waiting for him and gets kidnapped by Jafar who gives her magic and turns her into his minion, (not unlike what Rumple did with Regina).
Jefferson comes back, discovers what’s happened to her, realises there’s no way to get the real her back because that person is “lost”, (because he’s seen what happened to Regina and knows that there’s no coming back from that happening to you), and he ultimately has no choice but to leave her there and go back to FTL to raise their baby girl who is being babysat by the neighbours while her parents were at work. Explains Jefferson losing his wife because of his work. Explains why Jefferson hates WL. Even explains Regina’s little jab at him about not leaving family behind.