[macspoofing]

>because when he was here he was always attentive.

That doesn't sounds like the author. Kids will understand if a parent is away because they are working to make their (i.e. the kid's) life better. My father worked long hours, sometimes multiple jobs, all his life for little money, as did my mother. Even though they weren't around for some of my recitals or Christmas pageants, I respect them both that much more because I knew why they were doing it ... even as a kid. Kids aren't stupid though. If the parent is absent for selfish reasons, in order to fulfil their life and their goals, it will lead to bitterness and resentment. It will.

[barry-cotter]

Some people are bitter and resentful and would have had the exact same childhood you did and think their parents weren’t there for them. People in extremely similar circumstances feel very differently about them all the time, often enough within the same family.

[macspoofing]

You're correct, and we're all speculating because we don't know their situation. It could all be fine and the kids have other support systems ... but it doesn't sound good as written.