From what I understood juliet only destroyed one. By destroying it she took on damages. In order to reduce the damage on her lennox destroyed the rest of the barriers (97 of them) and took on a ton of damages so that Juliet can live. That's my understanding.
I don't blame you for the confusion, the writing on the point of the other lovers is quite muddled, and it feels like a retcon in later chapters. In the early chapters, it is very heavily implied that the ML, Lennox, is a total manwhore who swaps out women frequently from boredom and barely remembers any of their names, but Juliet is his one and only 'steady' who has stuck around for 7 years and tolerated the affairs. Lennox and his staff think about how Juliet is ideal because she isn't jealous or demanding, even with his divided attention, and how she isn't his normal, preferred type of flashy, lower class, and with big boobs. Other nobles, especially ones who want to marry Lennox themselves, constantly taunt Juliet that she'll soon be replaced, talking about how he always brings a new person to some annual ball that's the one and only public event he ever attends, and she's just one in a long stream of lovers. However, we never see Lennox with any of these women, and while the revolving door of women is talked about as if it were his current trend, later chapters assure us this behavior is placed very squarely 7 years in the past. So we get someone saying "oh, Lennox brings a new woman every year to the ball, and he throws her away after, just like you will be once he's bored with you!!" --while at the same time we're hearing that Lennox has actually brought Juliet as his partner for the last 7 years...and no one else. 7 years is a pretty big gap to still be mentioning these other women and expecting Juliet to be jealous. For example: We get the manservant being grateful Juliet doesn't get jealous or possessive of other women--while then being thankful she's the defacto woman of the house and only female around. It doesn't really make sense. The author probably wanted the drama of a manwhore and Juliet being put-upon by a jerk who isn't faithful, while acknowledging that the readers would never, ever go for a FL ending up with a guy like that. So, we get all of the characters talking about behavior from 7 years ago as if it were currently happening, to get that drama of Lennox being a bad guy, while Lennox is also being 100% faithful.