Mary Jane Watson was born in the state of Pennsylvania to a home which can be mildly called as unstable. The father of the girl was abusive and the mother fled with Mary Jane and her sister. The girl had an aunt, Anna Watson, whom she loved and appreciated very much. The aunt lived in New York City. It happened so that the mother of the girl passed away, so Mary Jane's sister had to foster two younger brothers. As for the girl herself, she moved to New York to her aunt. The girl knew about the alter ego of Peter Parker from the time when Uncle Ben died. She could see with her own eyes Peter crawling out of the window to catch the burglar who had killed his uncle. The girl could not meet Peter face-to-face till the time when their aunts arranged a date for them. Mary Jane had to hide her knowledge of Peter's secret. When Peter was at college, she dated another guy, Harry Osborn. At that very time Peter dated Gwen Stacy. Nevertheless, the girl did not stop flirting with Peter though she went on dating Harry. Soon Mary Jane broke with Harry just before Peter's drug problem which began in Amazing Spider-Man #96.
After the death of Peter's girlfriend Gwen, Mary Jane at last showed her compassion to the guy. She wanted to be with Peter and to grieve together with him. After some time they became a regular couple, though sometimes his lifestyle of Spider-Man broke their plans. In order to make Peter jealous the girl dated Flash Thompson. Soon Peter decided to propose to Jane but she refused. She explained her decision by the fact that she could not be happy with one man only. After that the girl disappeared from the book for some time. As for Peter, he had some girl-friends (The Black Cat and Deborah Whitman).
Mary Jane came back in Amazing Spider-Man #243 after staying for some time in Florida with her relatives. At that time she and Peter got very close with each other because both of them had some problems in their lives. Soon after a number of lies the girl admitted that she was aware of his life as Spider-Man. As she knew his mystery, she told him about hers. The girl told about her family. She said it was only a mask of a happy girl. She had used the mask in order not to go sane. After this talk both of them realized how close to each other they were.
Peter proposed to the girl once again in Amazing Spider-Man #290. The next series told about their happy wedding and honey moon.
After that the couple moved to a luxury apartment on the West Side. But their happiness was not long-lasting. The girl was kidnapped by a wealthy admirer, Jonathan Caeser. The girl was found and the man sent to jail. But it was not the end of their problems. Mary Jane had to give up her model career.