How to tell my friend to get over him

So I recently started a new job, and I’ve been becoming close friends with one of the girls in the office. She’s very high energy and extroverted. Recently she’s struck up a messy fwb relationship with one of the guys in our office, she caught feelings, he did not, it’s weird at the office, and she is constantly CONSTANTLY talking about this guy. She’ll text me during the workday about him, how he’s being annoying, or how she wants to plot to make him want her. She’s constantly showing me their sparse texts, and from my perspective, he seems very disinterested and only down for a hookup if it’s convenient. I feel bad, but it’s awkward and like painful witnessing her always giving him this much attention and it’s a tiring talking about our coworker all the time while also having to work with him. Both me and another coworker are giving her the “you can do better” encouragements but she just won’t stop. It’s making me dread her texts and feel like a bad friend. I also feel like I don’t know her well enough to be frank.