I sure understand how hard it is to work on what becomes a very boring project. The big pix here is that he's so involved in what you're doing.
My husb. always fully supported everything I did. I lost my husb. 5 yrs. ago & there is a huge hole in my life now. He used to be able to help me if I didn't have something placed right though.
Why don't you work on it in stages. Put it down for a bit then pick it up occas. Just put your love for him into every stitch & he'll know it. That should be motivation to get through the "boring" parts.
Pat G