This is incredibly difficult, because I have never articulated my situation in words to anyone before this. Here we go.
I am a married woman, 28 years old, and the mother of a beautiful toddler. My husband of 4 years is 20 years my senior. I feel this age gap, once a charming quirk of our relationship, is now a source of unhappiness. Notably, our unfulfilling sex life. I am a young, energetic, sensuous woman. Sex is very important to me spiritually, emotionally, and certainly physically. Tensions do build up! My husband is less interested, not just in intercourse but all the trappings of a passionate relationship. I estimate we “do it” about 6 times a year. All my attempts to arouse him are met with outright rejection or apathy. My self esteem suffers. When we do manage, the sex is uninspired and entirely one sided.
Before our child, we had an exhilarating attraction to each other. The moment I showed him a positive pregnancy test it came to a halt. I have come to believe it is the image of “mother” that turns him off. This infuriates me and I have come to resent his touch and his presence in our bed. I find my eyes wandering and my heart yearning for someone else who can revive these lost parts of myself. My question to you, dear readers, is do I follow these desires or stay in a desolate marriage bed?
We have tried counseling, our last session he said that he and I obviously have different ideas of what love is. I should add, if only to assuage my guilt, that he is a devoted and loving father, and otherwise is a very considerate and industrious life partner. If only I could teach my heart to be content with that!
LemonVibe 
Not much of an advice but I’m going through the same thing. My boyfriend’s 6 years my senior (which isn’t a big deal, compared to 20 but still) and has a lower sex drive than me. It’s weird how tired he gets after one round and almost immediately snoozes off the moment we finish. Maybe it’s because of his age, maybe it’s because it’s just him. Who knows. I don’t exactly have a super high libido but there are times when I get super frustrated about the lack of sex we’re having. We usually have sex once a month or so. Probably 8~12 times a year.
What I’m saying is, I feel ya. Although I love my boyfriend to bits and would never break up with him because he’s such a darn good person…it does get a little tough sometimes. Best advice I can give you: it’s not going to happen. It really won’t. There’s nothing wrong with you. It’s just a matter of stamina. You could have a serious discussion about it with your husband and talk him through the whole thing, which does work for some couples. If it’s simply because of him not wanting it, you have to tell him you’re getting sexually frustrated despite the huge blow to your self esteem. I talked to my boyfriend and although we aren’t as active as I hoped, we’re still getting there.
Hope things go well.
Honestly, I can’t tell what you’re asking – are asking for permission to have an affair or get a divorce? In either case, you don’t need anyone else’s permission. There are some schools of thought (ahem, Mr. Savage) regarding affairs that essentially state that if you cannot get your needs fulfilled in your marriage despite having tried a variety of ways to make it happen (counseling, talking, seduction, exploration etc.), but you still want to stay married because the relationship otherwise hits all the marks, it may make sense to open up your relationship. These schools of thought, however, in most cases stress the importance of getting permission (or at least discussing it with your partner and giving them some options) from your
partner before commencing an extra-marital affair, and being up front and honest about your relationship status (e.g.married but sexually open) with any potential sex partners.
Having got that out of the way, I have to say that you don’t seem that interested in being married to this man any longer . You don’t like his touch, you don’t like him in your bed, and mostly he’s a good dad and provider, but you don’t say much about whether you still care for him in a romantic way and it appears that sex is so integral to your experience of romantic love that without it, there’s not much left. I would encourage you to continue talking with your husband and attending counseling – perhaps going on your own as well as together. You both owe it to your child at least to try and understand where the other person is coming from and to navigate a respectful path towards divorce, if that’s where you are headed. I would advise you not to attempt to pursue
an outside relationship at this point. It will make everything else more difficult and destroy what is left of your marriage. Keep your libido under control until you can figure out the best path forward for yourself and your child. Best of luck.
I am a woman also in her 20s and I would say, be selfish. I don’t know when you married, presumably in your mid or early 20s, but essentially – he married you in your sexual prime. His was 20 years ago. He was extremely lucky to have your vitality and the best years of your life (ask yourself if he had made a similar commitment by your age, or, if you are his second wife, why you aren’t his age!), but they aren’t over, for you. Obviously I can give you the full feminist thesis on this or boil it down to a simple sentence – get out there and enjoy yourself! I am also the child of parents who suffered through an agitated and loveless marriage for the sake of their children, and it spared no one’s development, security or self esteem. Your child is a toddler and less likely to suffer the acrimonious effects of divorce now than when they become more aware of their home environment in several years. Don’t stare down the barrel of forty plus more years of boredom. Your interests are only going to diverge further in the coming years, and his libido and lust for, well, life will diminish alongside it.