Supergirl: Inside that heartbreaking breakup

Warning: This story contains major spoilers from Monday's episode of Supergirl. Read at your own risk!

Roughly a year after Floriana Lima made her debut on Supergirl, the relationship that viewers fondly dubbed "Sanvers" came to an emotional end during Monday's episode of The CW super series.

Though the duo were in the throes of planning their wedding, Alex (Chyler Leigh) came to realize that she did want the possibility of having children, something Maggie (Floriana Lima) never saw as being part of her future. Therefore, the two amicably parted ways. While painful, the split doesn't necessarily come as a huge surprise. Shortly after the season 2 finale, it was revealed that Lima would only return for a handful of season 3 episodes.

"We love Floriana, we loved having her on the show," executive producer Andrew Kreisberg tells EW. "When she first joined us, she was only willing to do a one-year deal. It was our fervent hope that she would sign on for more after having such a great year on the show, but she decided that that wasn't what she wanted to do. So we asked her to come for the first five episodes of the season so that we could properly wind down their story. We would've much rather have had — as Alex put it — the biggest, gayest wedding National City had ever seen, but unfortunately with Floriana deciding to move on, we had to tell a different story."

RELATED: Supergirl's Chyler Leigh on Maggie and Alex's fate: 'It is another chapter'

That story proved to be a modern take on relationships, one Kreisberg himself had faced in the past. "We very consciously did not want to kill her, and it felt like '70s TV to hear that she got a great job offer in another city and was leaving because of that," Kreisberg says. "We borrowed from a page of our own lives. I and one of the other writers both left long-term relationships because the person we were with didn't want to have children. They were very difficult breakups. It's very hard to leave somebody you're in love with, but when you know ultimately you won't be happy, even if you're happy now, that seemed like a true and real and emotional story that we could tell. It was a story without any villains in it, which we really appreciated, because everybody loves these characters so much."

For the record, had Lima decided to stick around, wedding bells would likely have been ringing by the fall finale. "In terms of what we would've done, we knew fairly early on in breaking season 3 that Floriana wasn't going to be with us for more than a handful of episodes, so we never really sat down and really tried to figure out what would the story line for the two of them be other than we had a vague notion of episode 9, the midseason finale, being their wedding," Kreisberg says. "But we didn't really get too far down that road, as I said, because it was never really a reality for us."

However, Kreisberg still holds out hope that the actress might return in the future so that Maggie and Alex could ultimately be endgame. "Floriana is always welcome to come back," he says. "If we come up with the right story, we would love to have her return."

RELATED: Supergirl's Floriana Lima addresses her exit

With all that said, Alex's story will continue. While Maggie was the catalyst for Alex realizing that she's a lesbian, the character is still in the midst of discovering who she is. "Ultimately, at the end of the day, we're telling the story of Alex Danvers," Kreisberg says. "As it turns out, Maggie was just one relationship in her life. There will be others, some sooner and some later. But we're continuing to tell the story of Alex Danvers coming out and making her way through life as a gay woman, whether that means new romantic interests or children down the road, we'll take it all as it comes."

In the meantime, the show will take its time in allowing Alex to grieve. "Certainly Maggie is not gone from the show in terms of Alex's reaction to it," Kreisberg says. "We would be doing a disservice to Alex if the loss of Mon-El [Chris Wood] affected Kara [Melissa Benoist] as deeply as it did and we didn't do the same for Alex, which is not to say Alex is going to be wallowing for a bunch of episodes. Maggie is still present just as if any one of us endured a difficult emotional breakup, that person is still in your life even if you're not with them anymore until they're not."

The breakup also sets the show up to delve deeper into the Danvers sisters' relationship, particularly the early years. As teased at the end of Monday's hour, Kara plans to bring Alex home in a bid to take her mind off Maggie. "It's actually the impetus for episode 6, which is this really fun, funny, cool episode where Kara takes Alex back to Midvale, the town that they grew up in, to regroup and recharge," Kreisberg says. "We get to see a flashback to the first adventure the girls went on when they were kids. It's this amazing episode, and we have these two amazing young actresses playing Kara and Alex. It's the episode that helps Alex get off of the couch, so to speak."

While Alex will soon be on the road to recovery, that doesn't necessarily mean she'll be moving on. "Just as in life, you wouldn't immediately jump into a new relationship after that big of a loss, we're not going to have Alex do that either," Kreisberg says. "That certainly doesn't mean that she's returned to being straight. Her life as a gay woman will continue to be explored, but I'm not necessarily sure we'll have her in a new relationship again this season. I'm sure next season, but I think that'll be enough time for both Alex the character, us as writers, and the audience — that'll be the time that all of us will need before we could replace somebody as amazing and powerful and iconic as Maggie."

Supergirl airs Mondays at 8 p.m. ET on The CW.