I also had the distinct feeling, reading below the surface of his account, which gives no details of the afffair at all, that she was he one who put the moves on him, acquiring for herself a pretty foreign boyfriend in the way that not a few Japanese women I knew did. (Or girlfriend, if they were gay.) That she had no idea what she was getting into is, well, the way things often go; at least she wound up married to him and AFAICT not pregnant, which is the reverse of the cases I knew. (Not the lesbians, obviously.) And of course I've met any number of clueless foreign guys who acquired Japanese girlfriends with no idea what they were getting into either.
I mean, Iyer may be less than admirable for anything I know to the contrary; but he notably has the ability to turn an observation around-- 'Well the Japanese do this, yes, but then observe how we do the other'-- and damned few white male Americans writing on Japan think to do that. Something to do with his first-gen outsider status as a westerner; and I think he deserves props for that alone.