Last sentence in whole show is she doesn't believe him about the person, so: a) was he cheating with secretary? b) he is cheating with someone else? c) she is just paranoid and he is not cheating at all? d) he is cheating with multiple mistresses?

By the jacket and everything it would seem like too big of an coincidence, so I would assume A is correct, but the last sentence caught me surprised a bit.

Btw the gas with oldest sister was really an accident or suicide attempt?

Btw thorough the show I couldn't help myself being reminiscent of Pachinko show, this felt like Pachinko Lite for people who don't want that much depth and want more fun.