So long as you're not spending money that should go to support your family, I don't see a problem. So long as you're not fooling yourself into getting involved emotionally - it's also harmless. Some guys just need more sex than is available via a traditional marriage. I know in my case, hugely attracted to my wife, was in love (at least for a long time), but I've always had a problem with long-term fidelity even before I got married (it's a flaw in my character but I deal with it). Using SP's seems like a victimless activity - there's no expenditure of emotion that should be reserved for your wife, and so long as nobody was left wanting because of the money spent - I never saw a problem. Also - I work in a high stress job, and sometimes - mid-day, especially if I had a particularly good morning - I just felt like getting my rocks off. Kind of a caveman adrenaline thing. So 80% of my "hobby" activities were mid-day quickies at a downtown agency or independent. To this day, even through the divorce (divorce has nothing to do with hobbying) - there's been no impact from my hobbying, financially or otherwise.