I thought it was pretty well established, maybe not in the original theatrical version, but in the Final Cut, it restored all the cut scenes of Dreyfus' character really being an alien in his own right to his family. His marriage wasn't the strongest and the I thought it conveyed just how much of a stranger he was for them. I think it made it all the more sad and tragic that the family unit fell apart because of him, if not because of the alien contact, but because he was a man caught in a situation he wasn't equipped to handle in the first place. The fact that he became obsessed with the cosmic call was all the more heart-wrenching, putting that above his family, compounding the already bad situation he was in.
Sure he had a family, but unlike ET, this film is more tragic in the sense that the family unit wasn't strengthened because of the encounter, but ruined by it, and it's partly due to the character flaws of the protagonist, and I think that's what makes this film so much more interesting than ET. And I think that's why I like this film more. It feels more mature like that. He's an adult, a grown man with children and a family; he should have his life together at this point. But his greatest flaw is that he never grew up (a recurring theme in the movie is Pinocchio), a man who saw wonder like a child but trapped by the confines of the "real" world, and in the end, it cost him everything but satisfied his child-like wonder and it's all beautifully, and sorrowfully, captured in the last 30 minutes of the film.
His last meaningful contact with another person, who genuinely understood him and loved him, was with Jillian, and he sacrificed that to capture and bask in that wonder that possessed him in adulthood, but ultimately, stemmed from his childhood. Something he never let go to his detriment. The film is very tragic in that sense.