> I didn't say that, I said that "increasing serotonin" is not why these drugs sometimes help people feel better.
Yes it is. Only some people don't have too little serotonine.
Yes it is. Only some people don't have too little serotonine.
One of the things that we're reasonably sure can cause depression is decreased levels of serotonin. That doesn't mean there's not other things which cause more-or-less the same set of symptoms.
EDIT: On a note related to your girlfriend... people can appear externally happy while being seriously depressed. From talking to me irl, you'd likely never guess that I self-harm, have no motivation to do anything, and wish I were dead. You can't blame someone for wanting an escape from that.