Very surprising book. The h falls in love with a Portuguese H and is expected to get used to living in a very conservative setting with a future mother-in-law who loathes her, an OW whose predatory and malicious behavior she is supposeed to tolerate for the rest of her life because the OW is an old friend of the family, and a society where blatant infidelity is widespread and tolerated. The likelihood of the H remaining faithful seems quite low despite the H's protestations and occasionally grudging reassurances. The h reaches her breaking point when the h has to go and retrieve her BF's husband from his mistress at a casino when the BF goes into labor and is on the verge of dying. When she gets there, she sees her husband with the OW.
After not receiving satisfactory answers from the H (he says that he was there entertaining clients and the OW just happened to be there, which I believe, but it really wasn't the point -- the H should have recognized how fed up the h was with anything that even hinted of unfaithfulness, and instead he's prickly and defensive), and more clashes with the OW and future MIL, the h returns to England and gets her life back slowly, although she's still pining for the H. After a few months*, he turns up, and here's where it gets surprising -- he has left his family in Portugal and has moved to England to be with her. He's transferred his business headquarters from Lisbon to London. They'll stay there for the forseeable future, until their love is cemented by years of happiness and nothing can come between them. (Although if I were the h I would only visit for my MIL's funeral.) I was really stunned it ended up that way -- I was sure she'd end up going back to live in an intolerable environment because she was so in love with the H that he was all that was important.
*I actually understand why he didn't get in touch with her during those months. They had talked everything to death, and he needed to prove his love through actions.
To answer the really important question, the phrase "alien corn" comes from Keats' "Ode to Nightingale" means someone who is alone in a foreign land or alien surroundings. I had to look that up.