corgi2 wrote: A few unanswered questions are left with me after the final episode... so like are they still "married" even though they didn't wed officially and what about when she starts getting old, he said he wanted to grow old with her, is he going to remain forever young or is he going to one day instead of disappearing every random moment be able to stay with her as it seems his return trips get longer and longer.
The only aspect that really be considered bittersweet is that he won't age and she will, but I think the entire message was to savor the time regardless of the outcome. Like you said, his trips are becoming longer and longer and I would say it's subtly implied that he is back for good at the end when he appears in the bed and says "I'm back."
The marriage was sort of glossed over, but they are still "married" and living together. Although I can't say if they were married for real, it seems pretty likely.