Ahhh, so confusing indeed. I have like three theories.
- Nao-chan was the parents’ kid during college and was the reason they decided to get married — unfortunately, the baby died before birth. (But then yeah, what about the mention of the “college friend?”)
- Nao-chan is the college friend who likes the mother. He’s probably bothering her to the point that she had no choice but to get married to the father as soon as possible, Her marriage frustrated Nao so much that it led to his death.
- The college friend is a girl and Nao-chan is her unborn kid with the father. By being “the reason they got married,” I assume that it’s because the kouhai and the father have already broken up by the time he got together with his wife (without the father’s knowledge that the kouhai is pregnant). It was only after they got married that someone notified the father and told him that “they” (both the kouhai and his baby) died.
Your theory about Nao-chan being the wife’s baby with the college friend is also plausible too — though I don’t really think she’ll forget her child’s name.
Anymore theories? I’d like to read what others think.
Confusions aside, it’s still a good creepy ep.