There's Wendy Richard's story "Green Card" where Superman marries Lois, but isn't there another one where he marries someone else, a police officer maybe? Memory is failing me. One of my college professors was wondering if the fact that Superman lacks a green card was ever addressed. To my knowledge (internet reserach!) it hasn't been addressed in canon but the fearless FOLCs have tackled it more than once.

That is Superman\'s Wife by Poussin, but it isn't about Green Card, it's to protect Lois.