Jennifer Morrison and Josh Radnor Jennifer Morrison and Josh Radnor

Jennifer Morrison knew it was coming, but that didn't make her final How I Met Your Mother episodes any easier.

"We all know Zoey and Ted weren't going to make things work. The way things ended, I thought, was very bittersweet. Everything was," she tells "I certainly would've loved to stay, but obviously that was never meant to be for their story line. I really was in denial on my last day! I felt like we were going on hiatus and I was going to come back. But if it had to end, I think they found a very cool way to end it."

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Yes, the epic breakup between Ted (Josh Radnor

) and Zoey (Morrison) will finally take place on Monday's episode (8/7c, CBS) — just a week after they traded "I love you's." But perhaps the abrupt change of heart is fitting for the combative couple who've spent all season on opposing sides of the Arcadian Hotel debacle. That changed last week when Ted caved to support Zoey in preserving the dilapidated building. "He made what turns out to be the wrong choice to join her side and we'll see him realize that," creator and executive producer Craig Thomas says. "It kind of goes down as a court case. There's a big hearing about whether the Arcadian is going to be destroyed so Ted can build the new Goliath National Bank headquarters and if it's a landmark. The episode is called 'Landmarks.' It's about what do we preserve in our lives and what has to fall down to make way for new stuff. Barney thinks new is always better. Ted is romantic and nostalgic. He wishes he lives in a romantic comedy from the 1940s, but he's falling for the wrong girl. It's the story of a doomed relationship."The split is not Ted's proudest breakup, Thomas says, as it involves him enlisting the gang to "do something devious." "They're really starting to fight dirty against each other over the Arcadian in a way we're hoping is very entertaining."

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Entertaining is also what Morrison thinks Ted and Zoey's relationship has been. Though they've been constantly fighting (or trying to avoid fighting) since they first met, the actress believes there is true love and affection beneath their bickering."I think it's obvious they love each other. Their issues are never personal; it's about work," she says. "At some point, you either thrive and enjoy that kind of conflict because you can have fun with it or it doesn't work. They're probably too similar. Neither one wants to back down. They both always have a point, which is what I think has been so great about how the writers have handled it. ... You don't know who to root for as opposed to, 'Oh, man! These two are a mess!' Sometimes people just aren't right for each other, but that doesn't mean you don't love someone. You probably can't sustain a relationship like that over the rest of your life, but for a certain period of time, there's fun to be had in those kinds of debates and conflicts."But the breakup doesn't mean we've seen the last of Zoey. Morrison, who figured out she was not the titular mother from piecing the clues together, will be in the season finale, which takes place in September, four months after their split. "One of the story threads in the finale is a very human thing about how you can be doing great in life, as Ted is when we show him in September," Thomas teases. "We like to think we're so evolved and independent, and it's shocking how little it takes for you to cave like a house of cards and think, 'Maybe I should go back to that life. It wasn't so bad.'"

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Currently, Morrison is not committed to return in Season 7, though her availability could be complicated if her supernatural fairy-tale pilot for ABC, Once Upon a Time, is picked up. "They certainly leave that door open. It's not like I die. It's like I get institutionalized!" she says. "Nothing so crazy happens that Zoey can't resurface in his life. I loved being there. I would work there every day for the rest of my life if they asked me to. The good thing is that I definitely have friendships with people on the set. ... Even if I don't [come back], I think there's always going to be a real connection and love between Ted and Zoey. She's one of his few long-term relationships. Those tend to be the impactful ones. At least that's what I'm telling myself!"