I think some of the reviews were way off, and frankly kind of disturbing. *SPOILERS *************************************** Beck's self-esteem issues was the reason Joe targeted her to begin with. He needed to feel important, and in control. He needed her to be helpless so he could feel strong. He was broken from years of abuse. The reason he doesn't latch on to Karen is because, Karen was a strong woman. She didn't need Joe. Joe frequently complains of having to "take care" of Beck but he is using this as an excuse to do terrible things and justifying them with her as the excuse.
Beck needed Joe to want her. She became bored cheated and left him, and only wanted him back AFTER he appeared happy with someone else.
Their relationship was totally codependent. Although YOU touches on problems of Millennials and dating, like social media and entitlement, it is a classic retelling of Domestic Violence and stalking, Just like every other Lifetime movie or series.