If you want rival couples to marry in harvest moon island of happiness does the first heart event have to be in year one

No, the first rival heart event does not have to be in year one, but it is better if it is because you cannot experience the first rival heart event if that character's heart level is above black. Although, you cannot experience the 2nd rival heart event until the 2nd year, the 3rd until the 3rd year, and the 4th and final until the fourth year. DO NOT EXPERIENCE THE FOURTH RIVAL HEART EVENT IF YOU WANT TO MARRY THAT CHARACTER. The fourth rival heart event is the wedding proposal.