The plot is not original and it does sound like a Wattpad story. Hell, it sounds like After. It's almost the same thing except it DOESN'T have Hardin's irritating accent, Tessa's fake innocence, and plain side characters. It's complex and doesn't glorify toxic relationships. The couple are both miserable and cruel but still come back to each other and yes, they have great sex... still wonder why they all do that. Unlike After, Tell Me Lies doesn't give us a toxic relationship disguised as a love story, it tells us straight up that it is an abusive relationship and about the lasting impact that person has over your life even though you guys are over. The side characters also deal with toxic relationships so it's more of a character study about this friend group rather than a great love story filled with obstacles and one-dimensional shitty parents.
It's better than After in terms of writing, and acting, even the sex scenes and the cast are way hotter. And it might be a bad show, I don't know. all I know is that I love watching toxic people destroy each other because they are so caught up in their own emotions and desires.