Well I found this;
"Jack Abbott and Victor Newman have always been bitter rivals in love and business. Jack married Victor's ex-wife Nikki, but their marriage was doomed because she could never get over Victor. Their child was born too early, and died soon after, due to an argument between Victor and Nikki when she fell down the stairs.
For years, Victor and Jack vied for control of Jack's father's company, Jabot Cosmetics. Jack was instrumental in the company's "going public", thereby allowing Victor's takeover. A deal was struck to return control of Jabot to the Abbotts, if Jack would abandon Nikki. But Victor tricked Jack, and the deal fell through. For revenge, Jack planned, with the help of Brad Carlton, to take over Newman Enterprises during Victor's absence but was caught by Victor. Victor collapsed as he was accusing Jack of this mutiny. Jack left Victor to die, but later returned to save him. Victor survived and the battle between Jack and Victor continued."
I guess it is a case of always has been and always will be.