Some studies show that couples in open marriages can maintain satisfying relationships. Rubin observed no differences in marital adjustment between couples in open marriages and couples in sexually monogamous marriages. Rubin and Adams reported no differences in marital satisfaction between couples in open marriages and couples in sexually monogamous relationships. Gilmartin likewise found no differences in marital satisfaction between sexually open and sexually monogamous couples. A study by Bergstrand and Willams found couples in open marriages had higher levels of satisfaction than couples in the general population.