Comparison level for alternatives falls under the Social Exchange Theory and is the idea that you can replace your relationship with a better one.
In the movie Bride Wars it begins with the two main characters at one of their friend’s wedding. As both of these friends get engaged and go through their wedding plans it snaps back to this friend and shows her becoming more and more dissatisfied with her relationship with her husband. By the end of the movie, at the wedding of these girls, this friend makes a statement to another girl that she just went through her first divorce and suggests that there may be more to come. Her attitude about relationships and how they are disposable and replaceable relationships demonstrates the concept of comparison level for alternatives.
You can find this movie through youtube or netflix.