Quoting Idlehands:" ^ Same here. I can't be offended by my DH's fantasies when I myself have them when we are having ... [snip!] ... common, whether they admit to it or not. It might not be a particular woman but boobs/butt/vagina (whatever floats their boat) "
I totally agree with you - I do wish that we were more educated on the functions of female and male attraction as I think it would save a lot of people heartbreak. I do think both sexes fantasize about other people/body parts/scenarios whilst being intimate with their partner - but as you said it has no reflection on the one you love.
Being such an understanding person this helped when my partner told me he was thinking of others whilst having sex with me BUT my god if I knew then what I know now about the fact that more or less all men do it but in a completely non malicious manner - I wouldn't have had to go through quite as much turmoil in my own head.
My partner and I are working on a more spiritual sexual connection now rather than visual - It's proving rather fun!