I can so relate to have projects that sat unfinished when it came to thinks that were important to me. The fourth house sat unfinished until it was time to put the house on the market. It was good enough for me to live with unfinished but not for someone to put up with. The next house when he did this again to me I called the most expensive carpenter in our area for a quote and when my husband returned home from a business trip I told him that on Tuesday I was having this room finished but that expensive carpenter. After he almost swallowed his fork and had regained his ability to speak, he asked how much it was going to cost. I calmy told him the amount and he replied, "I'll finish it this weekend I promise." He did and I never had to put up with an unfinished project again until he died.
It's just a suggestion but it might work for you too. Their ego can't take the news getting around that their wife really got him where it hurts, his wallet. It must be a thing about male pride having the most skilled carpenter, in the area, finishing his uncompleted projects. hehehehe
Anyone wishing to try this tactic is free to borrow my solution. It really worked for me.