Not gonna lie, I did not care for Leah. 
 I guess since she's not the original couple like Olivia and Caleb. I'm not rooting for her. She's lying and manipulative. She didn't even do it because she loves Caleb because she only lied and manipulated Caleb so Olivia didn't get him. She tried everything to prevent Olivia from being with Caleb. 
 What does she get out of it? A baby she doesn't like at the beginning and a marriage with no love returned. 
 I did want her to be happy especially with Sam but I'm not even sure that happened because 
 (view spoiler)[ Caleb's brother? (hide spoiler)]