He had a son with Aife, the sister and rival of Scathach, whom he defeated with the old "look over there" trick.
He also had sex with Scathach, her daughter, and many, many, MANY more women.
It got to the point where all the men got together to get him a wife before he could f**k all their wives and daughters. Cu got more tail than a toilet seat.
He never met Skadi as she lived and died way before his time.