Why would an Ex boyfriend, whom I haven't spoken with in years be disappointed because I'm married.?

[Good & Plenty]

I got to speak with a ex boyfriend from 13 years ago.
I happened to have a friend on my facebook page who knows him.
I told her to tell him hello not thinking anything else about it.
My friend said he ask if I would call him. I said sure.
We caught up with old times and it was great, however I could hear the
disappointment in his voice after mentioning my marriage.
After 13 years why would a person think that
life doesn't go on.
I didn't feel that way about him and his new woman and children.
I don't get that. He is really a nice guy too. Hard to believe his behavior.