Kirk Larson has John marrying Jean, daughter of John Stewart and Isabel Ergadia/MacDougal. Burke's Peerage says Jean married David Bruce (with no mention of another marriage). In fact the dates Kirk gives, in trying to work the two marriages for Jean, are a little stretched since David Bruce (b. c1392) was much younger than John Bethune, and John Bethune's son Archibald by (presumably) Jean Stewart was b. c1390/6. Plus the fact that John would be marrying his mother's niece!
Father: John BETHUNE , 1st Laird of Balfour b: ABT 1343 in Balfour, Fifeshire, Scotland
Mother: Catherine STEWART , Heiress of Holkettle b: ABT 1346 in Innermeath, Perthshire, Scotland
Marriage 1 Spouse Unknown