Gwenllian married Rhys "Fychan" AP GRUFFUDD Prince of Deheubarth, son of Gruffydd AP RHYS King of Deheubarth and Gwenllian II FERCH GRUFFYDD. (Rhys "Fychan" AP GRUFFUDD Prince of Deheubarth was born about 1127 in Dynevor Castle, Llandilo, Carmarthenshire, Wales, died on 28 Apr 1197 and was buried in St David's, Pebidiog, Pembrokeshire, Wales.)
Sources
1
Foundation for Medieval Genealogy, Medlands, Gwenllian.