Complex sentence: Jenna Maroney (Jane Krakowski) gives him advice regarding this, in which she explains that he sleep with someone so that he not be labeled as monogamous, leading him to try and have sex with Liz, but she refuses.
Split into simpler sentences: Jenna Maroney (Jane Krakowski) gives him advice regarding this, explaining that he should sleep with someone so that he not be labeled as monogamous. This ends up leading him to try and have sex with Liz, which she refuses.