Warning! Spoilers ahead for the finale of the Arrow-verse crossover event, "Crisis On Earth-X." Feel free to look away if you haven't watched the episode yet!
Well, we all knew, going into the "Crisis On Earth-X" crossover event on The CW, that The Flash's Barry and Iris would not have an easy time getting married. Luckily for fans, though, we did get a major wedding twist at the end of the crossover. Not only did Barry finally get to marry the woman he's been in love with for most of his young life, but Oliver and Felicity actually tied the knot after several relationship setbacks. I know! Let's back up a little so you can find out how this all went down.
As was evident from pretty early on, our heroes had a hell of a time beating their evil doppelgangers and the various Nazi baddies from Earth-X. In the end, Evil Supergirl simply overloads from solar radiation and actually blows up, Evil Oliver is killed by our Oliver, Barry lets Reverse Flash go (for some crazy, only-Barry-could-explain-it reason), Cisco uses his super-helpful breach powers to send folks back to Earth-X and the Earth-X portal to Earth-1 is out of commission.
Afterwards, Barry, Iris, Oliver and Felicity are in a park to send off Kara and Alex. Once they head back to Earth-38, Barry and Iris reveal that they've decided to give up on the idea of a fancy church wedding in favor of something simpler and less likely to get interrupted by a giant battle that kills their minister. Because they're pals, Barry asks Oliver if he'd marry them using his powers as mayor to make it official. Unfortunately, Oliver has to remind Barry that, since they're still in Central City, that wouldn't apply now, but they do know someone who's fully ordained: Diggle.
Barry then speeds to Star City and grabs Diggle, and, after he vomits (of course), he proceeds to marry Barry and Iris. Before they can kiss, though, Felicity pipes up and, get this, proposes to Oliver. After all her "I don't want to marry you Oliver!" stuff from last night, I guess actually watching them get married on top of the danger of the crossover touched something within her. Oliver, obviously, accepted, and Diggle marries them right there in the park as well, finally bringing the Olicity ship to a place that (some) fans have been waiting for for years.
Of course, with Oliver still in all kinds of kooky trouble with the FBI for his work as Green Arrow, this means that Felicity will never need to testify against him. So, really, this marriage is just a win on many levels. You can keep up with all the superhero shenanigans on The CW when Supergirl, The Flash, Legends of Tomorrow and Arrow return next week.