I forget anything that has to be taken regularly... meds, vitamins, birth control pills... I just forget. Also yes, it is very common for people with all types of mental illness to hit a "I feel better, I don't need these." Just like antibiotics. You feel better so you stop taking them even though it clearly says not to stop until they are gone!

May be a bipolar thing but I think it is more human nature. No one wants to be ill taking meds.