Why Marty McFly Should be Admitted to a Mental Institution (Back to the Future 3 Edition) (Part 2)
Welcome to Part 2 of my Back to the Future series. For Part 1, click here.
While Marty deals with the fact that he screwed everything up yet again, he also has to manage a lovesick Doc and cope with the terrible scientific decisions he's making because of Clara. One of these decisions is dancing with her at the town festival that night and almost getting himself shot by Mad Dog. Fortunately, Marty throws a pie tray into his hand making him miss Doc and set his sights on Marty instead. They set up a duel in the street Monday morning at 8 o'clock because Marty assumes he'll be back in 1985 by then.
Doc and Marty resume their attempt to get the time machine working again and in the process Doc offhandedly mentions to Marty that he shouldn't let his temper get the best of him and let people coax him into fighting; if he didn't then maybe he wouldn't get into the accident.

Not this accident.
So, at this point Marty has just saved Doc from being shot essentially by putting himself in the line of fire and Doc has just told him that he's going to be involved in some mysterious life-changing accident that he won't tell him about. After three days of time-travelling and having the fate of the entire universe on his shoulders, you'd think Marty might stop to take a quick breather and try to maintain his sanity. But before he can do that, Doc also tells Marty that he's made a decision to stay in 1885 with Clara essentially rendering Marty's entire trip there totally pointless. Marty convinces him to come back to the future despite his feelings for Clara and, for a moment, Doc seems to have his head on straight again.
But, Marty wakes up the next morning and Doc is gone. Marty finds him in the saloon apparently drinking away his misery due to losing Clara. Doc passes out and Marty has to deal with the stress of trying to wake him up in time to catch the train they plan on using to get back to the future. On top of that, he has to deal with Mad Dog, who has come to duel with him. Marty ends up bringing Doc back to life, defeating Mad Dog with a Clint Eastwood style bullet-proof-vest gag, and making it to the train with Doc. They get the thing up to 88 mph with some interference from Clara causing Marty to finally make it back to 1985 and Doc and Clara to stay in 1885.
So, Marty's finally back in 1985, a train almost kills him and destroys the time machine, his family is back to normal, he picks up Jennifer from her house who realizes that all of what she dreamt was real, avoids the accident he was supposed to get in, and returns to the tracks where the time machine was destroyed with Jennifer and explains how much he's going to miss Doc.
Just when Marty has lost all hope, Doc shows up with Clara, two kids, and Einstein on a time-traveling-train that can fly, turns into some sort of strange Willy Wonka type figure with a lesson to teach Marty, and simultaneously ruins the ending to my favorite movie series of all time.

Pictured above: The ruining of an otherwise flawless movie series.
If that's not a stress inducer for Marty, I don't know what is.
Well, there you have it. The conclusion to my way too long series on Marty's psychology and why, in the real world, he would end up prematurely grey in a padded cell at the age of 18. I hope you enjoyed this series. If you did, leave a comment. Depending on your reactions, I might continue to do these psychoanalyses of movie characters.