If I am under stress, I find sex to be very relaxing.
That said, the nature of the sex may be a bit different than usual. Not that I get kinky or anything, but the sex may have less of a sense of communication and more of a sense of urgency.
I think the common thread of these examples is that under stress, I need, more than ever, to lose myself in the act.
* I may just want to kick back and enjoy a completely no-obligation BJ. Lose myself completely in the sensation. I don't want to have to think about anything.
* I may want to pleasure my partner without regard to myself. Sometimes I can lose myself effectively by doing a massage, or by working over my partner with my finger tips and tongue, pushing her on to a climax. I may or may not want to join in when it's done. I'm sure this has all kinds of control-freak aspects to it.
* I may want to pretty much drag my partner off to the bedroom and jump right into things abruptly; again, taking control, but this time focusing on myself.
A lot is going to depend on what is causing the stress, I suppose.
There is a BIG difference between the women I've had in my life and me on "sex during stress." Most women I've known do NOT even THINK about sex when they are under pressure, their mind is on the problem. (I never understood this. I find that I can deal with whatever problem I'm having in my life better AFTER sex. The endorphins can help put things in perspective. I am relaxed and can attend to details. For me, it was much like taking a valium or an antidepressant -- with none of the inconvenient side effects like ED or Delayed Orgasm, but I digress)
I've only experienced one woman, back in college, who seemed to have the same kind of feeling about sex. I was 20, she was 30, and we hooked up several times when she was under stress, sex was CLEARLY her outlet.
My wife, occasionally, will seek sex during stress, but it may just be because, ironically, her sexual fulfillment had been put off too long because of stress. We have been undergoing a great deal of stress as a couple because of an aging and very ill family member who moved in with us for nearly a year. Not only was this an emotional situation, but we lost a great deal of privacy. Our house guest would go to the bathroom 3-4 times a night, and we had to keep our bedroom door open so we could rescue our guest if they fell or had problems. So, we would sneak a quickie now and then when we were pretty sure the elder was sleeping, but I knew it was mostly her being aware of how much sex helps ME relieve stress. I became the recipient of a number of quick, surprise BJs. Over all, the situation provided a very long dry spell for both of us.
As for her own sexual fulfillment, my wife is very loud, it's nearly impossible for her to be quiet unless her mouth is full, and she must move around a lot before she can finish. Every once in a while, she would push aside caution and pretty much attack me and please herself.