You pose a very interesting question, and I don't know if there has ever been any research done to develop an answer or even any statistics. Unless there is an underlying physical problem most doctors now consider bedwetting to be a sleep problem; the bedwetter just sleeps too soundly to wake up when he needs to urinate. Having satisfying sex is also known to relieve stress, so it is very possible that wonderful sex just before bedtime can cause him to sleep more soundly and increase the possibility of bedwetting. As for the increase from every 6 months to every week or two, maybe he didn't have such a satisfying partner then. Ask him to talk to his doctor and try a drug called DDAVP. This is taken at bedtime and slows the kidney output for several hours which might get him through the night without an overflowing bladder. If that doesn't work get some good diapers and make putting one on him part of your after lovemaking routine.