He is married to Alicia de Roos de Ros.
They got married.
https://www.geni.com/people/James-de-Byron-of-Cadney/6000000180501975828
Sir James de Byron, Knt.
Gender:
Male
Birth:
estimated between 1189 and 1269‰
Cadney, North Lincolnshire, England
Death:
circa 1300
Immediate Family:
Son of Sir Richard de Byron
Husband of Lady Alice de Roos
Secondly, before 18 November 1279, Alice de Ros married James de Byron of Cadney, Lancashire, knight, son of Sir Richard.
References
https://www.wikitree.com/wiki/Byron-192 cites
Royal Ancestry by Douglas Richardson Vol. IV. p. 490
Thoroton Vol.2 p.284 https://archive.org/details/historynottingh01thorgoog/page/n360
Richardson: MCA2, Volume 1, page 475, CLARELL, 3. GoogleBooks
The data shown has no sources.