Night one of the “Arrowverse” crossover focused on the West-Allen wedding, but unfortunately Barry and Iris didn’t get to live happily ever after. Their wedding was invaded by Nazis from Earth-X, and after the invasion took place they had to put their wedding on hold.
In the end, the heroes prevailed, and Barry and Iris decided that they would just go to City Hall at some point and get married since they already had a big ceremony. Barry asked Oliver if he could marry them since he’s a mayor, but he said that’s only something he could do within the limits of Star City.
But Oliver came up with a solution when he realized that Diggle could perform the ceremony, and Barry ran to Star City to get him.
After Diggle puked and figured out what was going on, he performed the ceremony, and half way through he was interrupted by Felicity.
During the rehearsal dinner for the West-Allen wedding in part 1 of the crossover, Oliver asked Felicity to marry him and she said no.
But during the wedding at the end of the crossover, Felicity asked Oliver to marry her, and he agreed.
Therefore Barry and Iris got married while Felicity and Oliver got married as well.
The Flash and the Green Arrow then kissed their respective brides as “Crisis On Earth-X” came to a close.
