Spoiler Alert:

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I got the impression Kyle had sort of ruined his career by sleeping with J.K. Simmons' character's wife. This, after an early episode where he shows some maturity by hanging out with Constance rather than going out to party with Hollywood-types.

As for whether the end was fulfilling, I think it is from Henry's point of view. Being that the show got canned, at least for all of his suffering and character development, at least we're left with a positive outlook on where his character might go.