It really depends on how you define "handling relationship".
Personally speaking I don't think gender or parenthood status defines how well someone behaves within the confines of a dating relationship. It really comes down to meeting someone who you are "into" and they want to spend time with you as much as possible.
Some single mothers feel they "don't have time" to date which would eliminate them from "handling a relationship" altogether!
Lastly one's effectiveness of "handling a relationship" is based upon how (their mate) feels things are going in the relationship.