What happened between...?

In the novel, Huw states that Mr Gruffyd leaves the valley to go to another country, and Angharad departs for South Africa to rejoin her husband. Must mention too, that in the book (and in contrast to the movie), they did conduct an affair of sorts, with Mr Gruffyd visiting Angharad most days and riding with her in the carriage, although not much more is mentioned beyond speculations by the gossipy townspeople and the housekeeper Mrs Nicholas as to what else they could have been doing.