Petunia Evans marries Vernon Dursley

Lily and James attend the wedding but things don’t go well. Petunia and Vernon do not attend Lily’s wedding a year later (Pm).

Timeline Notes

Lily is in her final year of Hogwarts (1977-1978) when Petunia and Vernon get engaged, so assuming that the wedding would be approximately a year later, Petunia and Vernon's wedding was very close to that of Lily and James (c. 1979). Harry and Dudley are both born in 1980.