Hi and welcome
!
A couple things here. Don't let her run all over (ie, away from him) when you're not home. Try keeping her confined in the room he's in so that she can get used to being alone with him without running. He should keep going up to her, just saying hi, giving little pets if possible, giving little treats, then walking away. Keep doing that. Then he should start picking her up, talking softly, telling her she's good, giving a little treat, put her back down in her bed. Repeat.
Also, have each of you wear bandanas/cloth/scarf so it gets your smells on it, and put both on her (safely) so that the smells are very close.
When you're both home, have HIM be the one who feeds her and have him be the one who gives most of the treats. Hand her to him often, even if it's just so he can hold her a few seconds, give a treat, and put her down.
Have you done an obedience class together with her yet...?