The events of Better Call Saul season 5, episode 8 saw Kim Wexler (Rhea Seehorn) meet Lalo Salamanca (Tony Dalton) for the first time, and backed up the idea that she'll testify against him to send the cartel boss down. Kim recently married Jimmy McGill (Bob Odenkirk) on Better Call Saul, which in large part was so that she couldn't be forced to testify against him (although there's undoubtedly love between them too). However, even before the marriage documents had been made official, there were hints that things would be ending sooner rather than later.
The judge when they were getting married made a pointed remark about Kim's middle name, leading to the theory that Jimmy and Mike Ehrmantraut (Jonathan Banks) stuck out in the desert, similar to Breaking Bad season 2's "4 Days Out", Kim does have a couple of key scenes, which the notion she'll move against Lalo.
Even before Kim meets Lalo, there are signs of her reaching a breaking point with Jimmy's work for the cartel. "I don't like this. I don't want you to do it," she tells him, each word painfully emphasized to drive home just how worried she is. Kim has went along with Jimmy's cons before - and even created some herself - but this is different. Kim is deadly serious in this instance, and it shows just how wide the gap is between husband and wife on this matter. At this stage, even before Jimmy has found himself out in the wilderness, Kim is already just about ready for drastic action to stop him working for Lalo.
That drastic action manifests itself in the form of a sit-down meeting with Lalo in prison, which unsurprisingly doesn't go well. Lalo is unsympathetic to her worries about Jimmy's fate, but what's more pertinent is his reaction to the fact that Jimmy told Kim what he was up to. Viewers are used to seeing Lalo incredibly laid back and relaxed, but there's a real flash of anger in this moment. This shows what Mike tells Jimmy: she's in the game now. And while that could spell terrible news for Kim, who may well have a target on her back, it also fits with the idea that she'll use her secret middle name to void her marriage to Jimmy, and testify against Lalo.
She's now seen up close just how uncaring Lalo is; she knows he'll be merciless to Jimmy. And she's also seen just how deep into this Jimmy is too, and her words alone aren't enough to pull him out of it. Kim isn't one to back away from a fight, and she'll also do whatever it takes to protect Jimmy - and herself. If that means heartbreak so that he can live and she can testify against Lalo to send him down for murder, she may well see that as a win. why Kim isn't in Breaking Bad. That may mean her death, but it'd be more in keeping with the show and what the character deserves to have her do the right thing, send him down, but still tragically be forced to leave Jimmy behind, turning him fully into Saul while her own end mirrors his as she assumes a new identity.