no, caused he never marries anyone else, and the other women he sleeps with was a trick they pulled on him by the other country. Its sort of reverse rapey in that sense. Concubine would mean the women would go into his household and live with him, which no one else does.
uhhh don't know what novel you read, but no he never marries anyone else in novels. And the only super obviously implied is one other girl he may or may not have (profb has a child with another)
Ray Hou - All I know