To me he doesn't sound as much rude as very socially clueless. Honestly, this smacks of autism that may have never been diagnosed and treated. Now my son is on the spectrum, but he could do much better than this and has learned to make good eye contact. Lack of eye contact is a big symptom of autism. It takes practice for them to look people on the eyes. I wonder, and I don't mean this in a critical way, if he is also a bit cognitively challenged. Even with autism, he should be very able to put the right age on a cake. Also...
My son is 24 and still likes the character of Sponge Bob. Some teens/adults do though. Pippa Pig is a show for toddlers. My three year old granddaughter likes it. That's how I know who the character is. My grand.
It must be hard to accept his challenges, I am sure, but it is what it is...he must have some sort of rather severe social communication issue and possibly low cognitive ability. I feel sorry for him. Would I want him with one of my daughters? NO! Would I try to get involved? No. I sort of know there's nothing I can do... But I would try not to spend time with him in a discreet way.
Can you see your daughter without seeing him?
Here's a thought. Maybe your daughter likes being more capable than him. It does happen. Maybe she likes caring for him?
This is so frustrating, I am sure, especially after losing your son and wishing, for very understandable reasons, for a son in law you can connect with. You have had a hard time yet you are still standing. Be proud of yourself and good to yourself please.
