Is there any psycologist who gona explain me how?

i've a friend of mine she has 30years old,since she decided to get married she start feeling upset depressed the same case was at the day of her weeding at the last minutes she wanted to stopp it her familly supported her but finally she get married but i remember that she was not understanding what was happen days after the doctor prescit her some medecines,she tryed to suicide a lot of time why?NO SUCH reall reason,she was preparing her doctorat,so the medecines help her so much and she returned the person that she was,when she was pregning she was not convaicted at all untill the 5month,now she has her baby,and infortinatly she start to feel the same dump feeling she is hallucinate,but less at it was in the first time,at the nature she's so much fragil her personnality is so weak,i really cant bleive how a human bean can be changed like that i thaught that i know what was the meaning of deppressing but i cant ever imagine that can heart people like that it 's really so painfull her doctor said before 2years we can not say that she was completly cured,it's so hard :