Even though I wouldn’t be terribly surprised to learn that this is the case, I think you’re making a lot of assumptions based on little to no evidence. That the notoriously private Worf didn’t mention Alexander to anyone doesn’t necessarily provide that they have a strained relationship; Alexander may very well have died and Worf suffers in silence over it. Conversely, Alexander may be a prominent member of the House of Martok and is well-known in the Federation so no one needs to ask about him.

I’d like to think that Worf’s emotional maturity means that he probably did or does maintain a better relationship with Alexander, and it’s simply that he didn’t come up in the context of what was going on in the story.

I wonder if Alexander eventually followed up on his desire to bring peace between the Houses and ended up dying instead of Worf? Maybe he somehow learned of Worf’s fate and decided to intervene, ultimately sacrificing himself to save his father. That might be part of why Worf has changed so much; embracing the things that Alexander believed in (peace and calmness) and making it a part of who he is in honor of his son.

I hate to think of Alexander as dead, but at least as a Klingon if he went out fighting for his father it was an honorable way to go.

That Worf is a bad father to Alexander is canon; I wish that Jadzia had lived and he could have had a second chance at fatherhood with her. I think his episode with Yoshi on DS9 showed that if he’d had a chance he could have become a good father.

The situation with Alexander was particularly challenging though. Kehylar hid Alexander from him until he was a young boy; she raised him to essentially hate/fear everything that Word venerated; then she was killed and Worf without more than a few days’ notice suddenly had an angry, hurt, and resentful son. His solution of sending Alexander to live with his parents was obviously a huge mistake because it exacerbated Alexander’s abandonment issues which stuck with him the rest of his life, and Worf wasn’t emotionally mature enough to either recognize or deal with it properly.

Anyway, I guess that’s a long way of saying that I understand Worf and Alexander’s relationship even though it’s sad and kind of painful. But I do think that Worf had it in him to be a good father eventually with the right partner. His bad luck with the women in his life certainly didn’t help though.