I don't know about stability specifically, but as a side effect it seems that both the Lexapro and Lamictal decrease my sex drive. Although, on the lower dose of the Lamictal it was potentially increased. Was hoping it was a sign it wouldn't mess with it, then got to the therapeutic dose and it's decreased again, but perhaps not as bad as on the Lexapro. Depression also significantly decreases my sex drive though. I had basically none months before even starting the Lexapro. Fortunately it hasn't affected my relationship too much besides the actual sex part.