The episode where they first meet is season 3 episode 18 "From Method to Madness". The one where they get married is season 5 episode 7 "Chick Cancer. It is also where Stewie was yelling at the dinner table.
It was believed he killed Olivia in Season Five's Chick Cancer however, he did not. She appears again alive & well in the first episode of the fifteenth season, The Boys in the Band.
Season 5 | Episode 7 | Chick Cancer
Peter Griffin: Husband, Father...Brother? & Saving Private Brian
'The Courtship Of Stewie's Father.' It is on the season 5 DVD
The episode is "Stewie Kills Lois."
Fore Father
Model Misbehavior
This happens in Stewie Griffin: The Untold Story.Specifically it's the episode, Bango Was His Name-O
Brian & Stewie's Emmy appearance & performance wasn't part of any Family Guy episode.
Season 6 Episode 5: Lois Kills Stewie
Season 7 episode 7
Stew-Roids
'The Courtship Of Stewie's Father.' It is on the season 5 DVD
The episode is "Stewie Kills Lois."
the 100 episode was stewie kills Lois now the next one is Lois kills stewie
Perfect Castaway
Baby Not On Board
Fore Father
Stewie Loves Lois
Boys Do Cry