Spoilers for the Season 3 episode "Damage" are below!

On the set of Supergirl in Vancouver (in the alien bar, no less) a dozen journalists and I were able to talk to the cast about a wide-range of topics including the advent of the Legion, the upcoming crossover, the rise of Reign and more (stay tuned!) But most pressingly, we wanted to talk to Chyler Leigh about the breakup of Alex and Maggie (Floriana Lima), which was such a painful but organic end to their relationship. As Leigh told us about “Damages,” (which was directed by Kevin Smith),

"It's a heavy episode. I mean there's no way around that, and just say what it is. It is a breakup. And honestly, in a lot of ways, it felt like a genuine breakup. I love Floriana to pieces. She's amazing. What we were able to do together for the community, but also for just like our friendship and being able to establish such strong characters, that goes beyond how many episodes we do together, you know? I'm incredibly grateful for that. So tonight's episode, yeah, it was heavy."

To that end, the two actresses were actually separated from the rest of the cast with their table read. “Kevin [Smith] really liked to make sure that we do this really well,” Leigh said.

“And so, he took Flo and I aside, and we did the table read just with us and Andrew Kreisberg and Jessica Queller. We wanted to make sure that the words were right, but the intention was right and the heart behind was right. Either way, any way you roll the dice, it's not going to be easy, and it's something that everybody felt. Not only that, but Kevin also said he thought it would be really great – and I totally agreed – to all of the scenes in one day. So it was a hell of a day.”

The Sanvers breakup ultimately came out of an issue of actor availability, as Lima wouldn’t be able to stay on as a series regular. As far as whether or not Maggie could come back in the future, Leigh said: “It’s not like an absolute closure, because no one ever knows exactly what's going to happen […] If [Lima] can come back, I know we would all love to have that happen. So if she's available, that would be fantastic.” She continued,

“You had to approach [this relationship] with the same delicacy to sort of end this particular chapter in Alex's life. It doesn't mean that Alex isn't still a lesbian. It doesn't mean that Alex's journey ends there. It means that this is a loss, but also a gain for herself and understanding who she is. And no relationship is ever going to be guaranteed. They're a hell of a lot of hard work. And regardless, there're ups and downs […] But with the ending of this particular place in their lives, they did come to an impasse. There are certain things that you're either always going to want or you're never going to want. In this case with kids, that's a pretty big deal. It's not getting a dog, it's not getting a pet, it's not fighting over what bird you want to have. This is a life-changing thing one way or another. When you have decisions like that, when you come across obstacles that are that big, you really have to choose what's going to be best for you, individually. Alex would never wish anything but the absolute best for Maggie and vice versa. That's really where, I think, you kind of see what is most heartbreaking about the ending of their relationship is how much they love each other and how much they want the best for each other. It's not like you have this screaming, you're throwing vases around the room. It's like you really see that the intention there is to allow them to be their best selves no matter what. I feel like we did a really good job with that.”

The biggest question from here on out is, of course, how Alex will cope with the breakup. As Leigh told us, it won’t be something that is dealt with quickly or easily, but it does lead Kara and Alex to head back to Midvale in next week’s episode to get back to their roots and be with their mother, as they’ve both been in grief. Leigh explains:

“It’s a really, really cool flashback episode where you see kind of the initial dynamic between Kara and Alex and how that was really difficult for them in the beginning and sort of what the catalyst was for the turn in their relationship. But with that, you kind of see Alex going back and really having to figure some stuff out. But that's just the beginning of it. I think there was a fine line, I think there was a balance that we really had to establish in kind of saying, 'OK, we don't want to be Debbie Downers all the time. But at the same time, there's a reality of that's an incredibly significant relationship.' I mean this is the first time Alex ever really said 'I love you' to anybody, let alone get engaged and have wedding talk and all that stuff. So you see her sort of like go forward and go back, and then go forward and go back. I think there's a pretty good balance with that. We had a lot conversations about saying that and keeping that authentic, and what that would look like in reality.”

Basically, there will be lots of ice cream, pizza, and couch scenes, with Leigh admits are her favorites. “The great thing about the sister dynamic is that regardless of what circumstance they're facing, they're always going to be each other's champion […] So you do get to see a lot of that really, really sweet scenes with Melissa that I'm just gratefully appreciative of. She's a sister. So it's great. We always have fun regardless, whether we're crying, laughing, or whatever it is.”

Leigh also addressed what the Sanvers storyline has meant to fans, and how important it was both for the way it was told and how natural it felt.

“That's the biggest thing that I've been so worried about is that I don't want people to think that this is the end of something really, really significant and important. It is really just the beginning in a lot of ways. I hope people can really latch onto to that and hang onto that. Almost like Alex in this situation, you can't ask people to sweep it under the rug because what we did, I feel – maybe I'm biased – but what we did, I feel was pretty groundbreaking, and to have such a strong relationship, I feel, portrayed as well as we did, I think we did a very great justice to that storyline and for the community. The hope, honestly, is just that people can see what it was and celebrate that just as much as I do and I know Flo does, and really be able to grow from here and just see what comes next for Alex. That's my hope.”

Supergirl airs Monday nights on The CW.