I watched a video a psychologist discussing CW (thank you
@Jessthinkin). Her opinion is the same as many on here. CW was probably a habitual cheater, he never thought about leaving til he met someone that he wanted more than Shanann. Her 5 week absence let him try out life with the new girl. He was undecided til he went to NC, being with Shanann and the girls did not change his mind, he decides he wants them gone, he starts to play nice to get her guard down.
What I found most interesting was her theory that the gas can and rope were going to be used to blow up the tanks. He puts Bella in first, realizes the tank is almost empty, so he decides to put CeCe in the other tank hoping it will be more full- why they are in separate tanks. Co workers show up or something keeps him from being able to ignite the tanks.