Spouse has confrontation fear

Really wanted some outside perspective on how to find a solution to this. A little back story is my spouse does anything they can to avoid confrontation. I normally wouldn't be worried about this, but It's unhealthy and affecting our relationship. They have trouble saying "No" to family obligations , clients and friends to the point where it ropes us into very extreme favors and happens at the most inconvenient times, that it starts to interfere with our work. We've had discussions about it, and how to distance ourselves a bit to avoid people asking, but then I just find that my spouse will commit to things behind my back. Which in turn causes issues between us. Favors that consist of doing free work for friends or extra free things for clients when we lack the time to deliver on the said promises resulting in frustration from family, friends and clients. I think it stems from their ADHD and need to "people please" at any measure. It's hard for me because I end up filling like the villain when I give logical answers as to why we can't commit to all of them. And unfortunately it leaves us on two separate pages. I do my best to allow favors here and there, but we just keep getting taken advantage of as generally the people asking the favors don't have boundaries and it leaves me very upset with no solutions and no one to understand. I just need some guidance from anyone that has experienced this and maybe what they used to compromise. Or if there isn't a compromise , how to cope with this. I just have too much on my plate and with endless favors it just continues to grow.