I will concede the point that there are people who can laugh and have severe psychological issues like Deadpool or even worse Joker. But you also have to consider Peter’s job: Dealing with bad guys almost every day. If he makes a mistake people die (and that is not just Gwen etc, but average people walking down the street), the psychological stress is enormous. Watch a movie called ‘Running Scared’ with Paul Walker and Vera Farmiga. Walker is an undercover agent who infiltrated the mob for 12 years. Even his wife ( Farmiga) and son had no idea. He had to lie to them, every single day ( sound familiar to Spider-Man readers?), and he knew he could not slip up because he would put his family in jeopardy ( again sounds familiar?). Fortunately for Walker ( and a Russian boy named Oleg ( watch the movie and you will see why)) Farmiga was a strong woman, and can handle difficult situations. Taking this to Spider-Man, maybe without MJ, Peter goes full Frank Castle ( a character created by Conway only 7 issues after ASM 122), but the point is, in that issue she grew up and stopped Peter from acting on his worst instincts. But Peter thanks to MJ and now Theresa, does have people to talk to that he can trust, and along with the growth of Miles should have things easier ( provided the writers do not go Dan Slott on him).