There is physical dependence caused by the release of the "pleasure hormones" dopamine and endorphins when dressing. Once we get accustomed to the pleasurable feelings we've experienced (especially when sex or intimacy are involved), we tend to crave those feelings again. So while not "addiction" per se, even when we can't figure out why we do it, we always want to go back and do it again. And as long as it's not hurting anyone or getting in the way of an otherwise good relationship, I say why fight it?