Ah yes, another segment of attractive girl who's actually pretty bad at things and her mid/nice-guy love interest to the rescue. Welcome back, Komi-san.
This is a hyper dramatic premise to say the least.
I can believe that a woman would be sociopathic enough to sacrifice a guy's reputation just so she could get with another guy.
I can't believe so easily that the other guy would instantly believe her over his friend of 2 years, but maybe he...