That's not a problem. As I mentioned above, he will give me a massage to warm things up. Foreplay is not an issue and he's very willing to do other things for my pleasure. But I want to really be able to get into it (the sex) but I tend to hold back or there is a lot of stopping when I just want to go at it (sorry for TMI) but feel that I can't really get into it because it will cause it to end too quickly. Again, we've talked about this for YEARS.
A friend of mine was with a man who would go off in minutes when they had sex, so the way they handled it was this easy...they just did it twice. The first time, he'd go off in minutes as expected, and they both just got into the quick frenzy of getting him off that first time. Then they would rest for a bit, he would give her oral or other play, they would make out and then soon enough, he'd be ready again. The second time then would last much longer and they could both get satisfied.
At other times, he would just get himself off an hour or so before sex, and that would then usually make the sex last a good time longer than normal.
To accomplish this though, they had a couple of things that I think are necessary....they were not embarrassed or upset by this. They just considered it a fact about the way his body works and worked with it without any shame or emotional side effects. They talked about it. "Hey let's have sex later, will you go get yourself off first please, I can help if you want!" was a typical way for her to initiate sex, for instance. It just was a part of their sex life and it didn't mean anything was "wrong" with either of them.
It sounds like you love your husband but are frustrated and sad about how things are going, so I don't know if you two would be able to implement something like this, but it was worth suggesting.
You mentioned you feel attracted to someone and it may be mutual. This is a very slippery slope, and per your words, you can feel it....you know this is a potential hazard to your fidelity.
Whoever it is, I would advise you to cut them out of your life. That's really the only way to get over a crush like that. I know you probably enjoy the feeling of attraction and being turned on by the thought of better sex....it does feel good to fantasize, of course. But seriously, you will be very sorry later if you don't cut that off completely and just try to either fix your marriage or figure out how and when you can safely leave the marriage.
Fantasizing about a particular person you know in real life has a way of making that fantasy turn into an affair. Though the reality of an affair is such an ugly thing, you would never believe it was the same original fantasy. What feels like a light fun adventure, suddenly turns into the end of your life as you knew it, including breaking the hearts of everyone who loves you.
It sounds like his general grumpiness and edginess is a problem and without him working on that, you probably won't be able to improve things too much. So I would focus on this area for now. He either needs to show some willingness to work on his attitude (whatever that takes, he may need to see a medical doctor, he may be low T or have some other condition that is causing his grumpiness, he may need counseling, anti-depressants, etc), or he needs to just be able to say "this is who I am, grumpy is what I am now, take it or leave it". That way, you could at least know he is not willing to work on that and then it would be up to you to decide if you want to stay with him for the rest of your life or not, knowing he won't change. Not having false hope, in other words. He either needs to work on it and give you hope or let you know there isn't any.