PinkCosmos
Gloriany - SS is about 40 now (according to my calculations) and GF is about 35.
SS treated my husband really badly (in my opinion) during the time they lived in the flat. SS was not interested in maintaining a relationship with my DH after DH split up from his mother. My DH did try but the effort was all one sided.
SS has not even seen his own son so I don't know why my DH should be regretting the past, other than regretting ever taking him on as a SS.
During the nine months they lived at the flat, the effort was still all one sided!
PinkCosmos I don't think the reasons why contact is lost really matter. No one who has responsibility for a child for 10 years can ever really totally distance themselves. Especially if that child grew up to have problems.
The regret is looking at the 6 year old who is now the age his father was when your DH was his step father, and thinking about what happened to the SS. He may think if he is involved in the child's life the child will have a better future than the SS. The fact that the SS hasn't had contact will only make him feel worse. The fact that he tried with the SS and failed time after time won't be a comfort. He may still feel the child deserves something.
I think if you could just help your DH by getting him to talk about how he feels and without insisting it isn't his fault, because he may be absolutely aware of that, and still feel an emotional responsibility it would help.
You could at the same time ensure you are personally financially protected, because the mother may be after money , so I think it is important.
But whatever is happening I think your DHs actions in the past and now show he does care about these people.