Generally the wellbutrin is added to whatever AD you are taking at like 50-100 mg every AM. The reason SSRI's cause sexual problems are 2-fold. They bind solidly to one of the sub-serotonin receptors (there are many, and I can't remember which one), and this makes it hard to achieve orgasm, and is simply biochemical. Also after a few months alot of people notice a decrease in desire that has to do with downregulation of dopamine receptors. For some reason wellbutrin tends to fix both. I have had some luck with BuSpar and trazadone as well.