My guess would be if this is based on an actual monarch it would be Edward IV. Although technically he was only married once there was an alleged pre-contract with Eleanor Talbot, which was regarded as tantamount to marriage at the time. He was notoriously promiscuous, but apparently prided himself on his ability to woo his mistresses rather than force them.

However historic ballads, especially royal ones use liberal amounts of poetic licence, political propaganda and down right lies - just look at Queen Eleanor's Confession, absolute twaddle but a great ballad all the same.