X-Men #106 featured a fill-in story by Bill Mantlo and Bob Brown. However, for it to fit in with their current story, Chris Claremont and Dave Cockrum devised a two page framing sequence that replaced this splash page.
According to an article in Marvel Vision 19, the wedding of Cyclops and Phoenix was originally scheduled for X-Factor #66 in May of 1991. An editorial decision was made to postpone the wedding so it could take place in X-Men. However, this cover by Whilce Portacio and Jackson Guice was produced before the event was cancelled.
Due to the synchronicity of having several recent posts featuring Jackson Guice art, I've decided to make this an official Jackson Guice week! Here's a wonderful poster, courtesy of Sean Howe's tumblr page: