Frustratedandconfussion, I am sorry your husband is not satisfying you in your love life, but instead if thinking about cheating just for sex, please try to educate him and tell him what you want him to do for you. Fighting and being resentful will not help, but if you coach him I am sure he wil respond better, certainly, it would be better than having an affair which it would bring a lot of more complex problems into your marriage.
My wife and I are in our mid 40s have been maried for 15 years, and our sex life is the best ever. It has not always been this way though as it took me some time to learn how to be in control of my desires for a quick relief instead of pleasing her. I have educated myself by reading materials, we have been in marriage retreats many times, and have talked to her about things that I feel I need to know in order to be a provider, husband, lover, and friend to her. It requires a lot of proactive work, on both parties part, to build a strong marriage.
As far as our sex life goes, we make love at least 5 times per week, more often than not we have it every day, from time to time more than once a day. I would say that she reaches orgamsm at least 75% ot the times, which is satsfying to her and to me because even those times when she does not reach one she still enjoys it very much. This is possible because our objective is to please one another not our own selves. We have even talked about fake orgasm and have agreed that those are not necessary in our relationship since we know that those times when, for whatever reason, she cannot reach one she still enjoys it and so am therefore no need for her to fake it.
I hope this helps. Take care and rember to ask for the things you want and need, but in a way that is not confrontational. If needed, find a marriage counselor to help you both. Some men need more trining than others, but for the most part, every man can learn to please his wife.