I can only answer for myself, I looked at other women in all of my relationship, all of them were serious, and had a grand emphasis on commitment in them. Looking at other women wasn't a fantasy thing, it was, feels naive saying, mere aesthetics.
It feels great to look at great looking women, and has nothing to do with sex, or having a commitment, it is a relief, a pleasure, and a few of my ex understood that. I remember we used to walk around just to search and report of beautiful women on the street, it was great, till we got to the point we included men in the activity, then the whole thing became an argument that had something to do with feminism. Not commitment issues, just feminism..