Joe Osae-Addo, a highly gregarious, Ghanaian-born architect, was living in Los Angeles, designing buildings and acting as the unofficial social coordinator of the local architecture scene. But on a visit to Ghana in 2000 he ran into, and subsequently fell in love with, Sara Asafu-Adjaye, an old high-school classmate who was living in London. The two embarked on a long-distance relationship, and...