In The Walking Dead season 11's part 1 finale, "For Blood", Leah decides not to go with Daryl following Maggie's walker assault on Meridian - but why? During the episode, Daryl reveals to Leah that he has been working as a mole for Maggie before offering her a chance to run away with him. After killing Pope in order to save her fellow Reapers from being caught in the crossfire, Leah turns on Daryl by pinning Pope's death on him, setting him up to be a target for the remaining Reapers. She then continues on with the assault against Maggie, with the finale ending with her firing rocket-armed arrows into the horde, Maggie and Negan among them.
Introduced in season 10's "Find Me", Leah leaves a huge impact by being Daryl's lover during the six-year time skip. Returning in season 11's "Rendition", she's part of the Reapers and has captured Daryl. Throughout season 11 part 1, Daryl infiltrates the Reapers in order to gain intel to aid Maggie and his group, while also trying to rekindle his bond with Leah in hopes of keeping her out of harm's way. This all comes to a head in "For Blood", where Leah proves to Daryl where her true loyalties lie.
While Leah may still care for Daryl, she chooses her loyalty to the Reapers and ultimately to herself. Her sense of family is what keeps her loyal to the Reapers. The betrayal she faces at the hands of people she cares about (such as Pope and Daryl) is what pushes her to rely on herself. Thus, Leah's love for Daryl takes a backseat to what she believes needs to be done.
During her time on The Walking Dead, Leah is shown to have a strong sense of family and loyalty. This is evident in "Find Me" when she discusses the grief over her son's death and finds love with Daryl, building a family of sorts with him and Dog. Most apparent, though, is when Daryl sees her with the Reapers. In "Rendition", she is clearly broken up over the Reapers lost in the conflict with Maggie. She is also unnerved when Pope murders one for being what he perceives to be a coward. Through Leah, viewers see that although the Reapers are ruthless killers, they share a bond that shows they care for one another and stay loyal to their core. Despite Leah being in love with Daryl, the Reapers are her true family, and for Leah, family comes first.
That being said, Leah comes to realize over the course of her arc in The Walking Dead that the only person she can truly rely on is herself. This is primarily through several betrayals she's faced throughout the series. In "Find Me", she gives Daryl an ultimatum on whether or not he'll stay with her. When he does not commit, she leaves and returns to the Reapers. When Leah discovers that Daryl's been lying to her about his allegiance to Maggie, she turns on him. Likewise, she faces a similar betrayal from The Walking Dead's Pope, who not only continues to lack concern for the lives of other Reapers but even leaves her inside a burning building with Daryl. When Pope puts Reapers in danger to take out Maggie, Leah kills him. Between Daryl's lies and Pope's callous disregard for her and her fellow Reapers, Leah chooses to let go of both of them.