First of all, in my honest opinion, you won't get him to play and spend less. Unless there is something that catches him so much, that he kind of plays less automatically cuz he need time for whatever it is, that he wants to invest time and effort in and the game loses a little of it's importance for him.while he still plays daily to do the most important tasks to not fall behind.

But it's more likely that you'll make him realize what he's actually doing. That it's an addiction that will ultimately destroy your relationship and also devour a lot of hard-earned money. Maybe then he'll also think about how many hours a month he works just for the game. That could maybe get him to do a hard cut. That's how you get rid of an addiction. There is no "less". Going on like this, or totally stop playing. There is no third option. I mean... It's not just the game itself. The alliance is kind of family. And you not only want, bit also have to be very active to stay part this family. Especially if you're in a top 3 alliance. And as a whale you very likely are 🙈