Sex - I think it is different for everyone.
For many of us we struggle with our new image, and that maybe we do not like our saggy bits. You also know that those breasts were used for feeding, so somehow (in your mind) you may struggle to go well, they can also be sex toys.
Obviously I am not speaking for everyone.
But for me there was a shift. I view my body differently, I am less likely to be "swept away" because I live more in my head now even than I did before, so tha tis difficult.
I also am often exhausted, and even if the door is closed, I expect a child to appear.
I can't tell you how many times during an act, I have had to leave because one of my kids has gone to the bathroom and is screaming for me to come and wipe thier ar*s - somehow that image stays with you.
I think being intimate and being unrestricted is harder when you have kids.
I think you have to work harder at your relationship to make those intimate moments more for everyone.
Sometimes however you are so tired from it all, that you do not have the energy to do the work, and sometimes just want to be left alone to read and drink your cup of tea.
However some times sex next to the pool at night when the kids are in bed also seems like a good idea.
So it depends on the person, depends on the situation and depends on which way the wind is blowing.