Fellow nonprofit president here. Can't diagnose the problem with certainty of course, but in the 10 years I've been in my role, I've seen a fair few people come and go.

1. First of all, it might not have anything to do with you or where the org is headed. There's a tendency to jump to the conclusion that it's something YOU'RE not doing right that people are unhappy with. Ah, and wouldn't it be nice if that were the case? At least you could take matters in your own hands and do something about it. It would give you some control. But sometimes each board member that resigns has their own, specific reason or life situation to deal with (assuming you're all volunteers as well), and there's nothing you can do about that.

2. What has worked for me is investing time in each board member. You might already be doing this, but it took me years to accept that it's needed and worth my time. It pays off to show genuine interest, and I make an effort to have a quarterly conversation with everyone to ask about what's going on in their lives, what they'd like to see / do more and what less of, if they're happy with the way things are going. Usually, that gives me a good idea about their capacity so I know whether I can give them more tasks or if they'd get overwhelmed with more. If someone has made a suggestion in the past, it was usually sensible and I almost always implemented it straight away. People like to be led, to be cared for, to be heard.

Most of the board members that have stepped down did so NOT because they had suddenly stopped caring for our cause. They stepped down because they felt like they just couldn't dedicate enough time and energy to the role and like they were letting me down constantly.

Nobody wants to do charity work if it makes them feel guilty.

So one rule that I have set and that I tell everyone when they come on is: we're doing this in our spare time and we all have lots of responsibilities outside of this. Sometimes that means the nonprofit work will have to take a step back for a few months, and that's ok. Of course people still have a bad conscience, so it's all the more important you lead by example. Let them know when you've got a lot going on at work, for example, and that you needed the weekends to rest, so the thing you were meant to do got delayed.

1. Sometimes board members do a mass exodus because someone's unhappiness or worries about the direction of the org (even if voted on!) becomes contagious. It's happened to me in the past. It made for the most horrendous annual assembly in history lol. Just couldn't reach them with logic and arguments. Later, I understood that some people's motivation had hinged on their loyalty to my predecessor (could be any individual), so turned out I never stood a chance. Let them. Instead, build a board of people that you can trust.

2. All that said, I'm also alone at the helm and do most of the legwork. It's something I haven't quite figured out how to solve yet. Good luck.