Instead of wondering and second guessing yourself that you made a wrong decision, why don't you try to improve your marriage??? I don't understand!! NO ONE IS PERFECT! Go to counseling and express what is lacking in your marriage and see if you could improve it. It sounds too me he is great in all parts but lack sexual chemistry...is it just his looks? his size? frequency of encounter? What is it? Why do people give up so easily in marriage? Give it a chance, no marriage is perfect, you have to work at it. Do you think the next guy you meet is going to be better??
Go to counseling and dont be a coward in taking the easy way out. If you really do love him and sex is the only lacking aspect, your marriage can work.