Thank you for all the comments and anecdotes. This has been helpful. A few people have asked questions so let me take a minute to answer a couple of those.
@librarylady, DH made an interesting comment last night as we talked about this. He feels this is partly his fault for not telling DS "no" often enough. We made decisions jointly but DH always let me be the one to break the news.
I'm not sure I would call him distant when the kids were younger but I seemed to have a much better relationship with them as children and they have turned to their dad as they grew older.
@hithere as for the "golden child" comment. DS is the 3rd child of 4, 2nd son. His oldest brother has Aspberger's, his sister has weight issues related to a medical condition, and youngest child had a skeletal birth defect that required surgery but he is otherwise fine. DS was the good looking athletic one who taught himself how to do magic, sculpting, parkour, and play guitar. He was always the kid everyone wanted to hang with. I didn't treat him differently than the others. Anyone with more than one child knows that the kids are constantly on about fairness so that kept things pretty much in check if one asked for something that the others didn't also get or have.
A situation where we helped and it wasn't good enough? The most recent involved the upcoming baby shower. DIL's sister is hosting and we were invited but not asked to do anything else or if the date was convenient. (It isn't as I had committed to a craft show planned where I sell jams, scones, etc. and had to cancel. I'm self employed so it was a day of lost income.) He called asking for contact information for aunts, uncles, and cousins. I told him who could be contacted on FaceBook since the shower is an e-vite. I also told him who would need a paper invitation because they aren't on FaceBook and I would get him the addresses. I hear nothing from him, DIL or her sister for weeks and encourage husband to communicate to be sure he understands how to connect with those they want to invite. Still nothing. Then this week when I reached out to him again I get a screed about all the family and friends who are willing to help them out and he had expected that we would do more. It was quite harsh.
I didn't respond because I wasn't sure what to say and the next thing is a nice message thanking me for clearing up the invitation issue and asking are we planning anything fun for the evening, looking forward to visiting this weekend, etc.
I have thought several times that this seemed emotionally abusive, which seems an awful thing to say. Yet, I have enough training in abuse dynamics to understand why that is.
And, as for the comment that we didn't trust him to repay the loan? Well, we had cosigned for one loan for his first quarter and explained that it was all we could do. We had also helped him and the other kids with vehicle loans. He is the only one who has missed payments or has been consistently late so I think we had good reason to be wary.