Liz cited her need to clear the air and make things easier moving forward on The Bachelor, but something tells me revealing her past with Nick had a little bit to do with wanting to lay claim to her own connection story to the Bachelor. So when Liz told Christen about her hookup with Nick on The Bachelor, she was partly trying to clear the air and likely also trying to humble brag. Can you really blame her, though? Corinne spent the day alternating between making out with Nick and talking about making out with Nick and having him feel her up in the pool. Then, there were the other women who'd been able to sneak in kisses of their own with the Bachelor, and still Liz was left wondering what Nick's feelings toward her even were. Naturally, she had to clear the air, right?
Instead of clearing the air and moving forward, though, Liz telling Christen about her hookup with Nick on The Bachelor created more drama than there had been yet in the season. Even if Liz's intentions were innocent and she had truly meant to just be honest with everyone in the house, some things are better left untouched until you can at least secure yourself a Week 2 rose.
Christen was shocked at the revelation and at the time, it seemed like she didn't really know what to do with it. Luckily, it didn't result in a big outburst between the women and Liz alone, but it would have come out sooner or later anyway. Nick made it clear during the group date to the Museum of Broken Relationships that he did want to broach the topic about his past with Liz eventually, but he likely didn't expect it to happen so soon in the season.
Liz kind of dropped the ball by revealing the truth to Christen about her hookup with Nick, but that doesn't really excuse the cold shoulder he gave Liz while she tried time and again to start a conversation with him on the group date. And this was even before he knew she'd revealed the truth about their past together. In a way, Liz had succeeded in clearing the air and moving forward from her hookup with Nick, but not in the way she had hoped.
Later, Liz revealed the truth during her faux breakup, which was news to all of the women except Christen of course, and it was a way for Liz to make sure Nick finally knew where she was coming from. It probably wasn't the best way to get it all out there, but in a way, he hadn't left her with much of a choice.