Him and Lilly broke up a while ago, not because of the other girl (Jessica), and he feels guilty because he feels like he's betraying Lilly by opening his heart up to another girl. I tend to picture him saying to Lilly "I'll never love another woman," during their relationship, and feeling like a liar because it turned out not to be true. I don't feel bad for Lilly, she probably doesn't feel betrayed, and may even be happy for him that he is no longer hung up on her, his ex.
Him and Lilly broke up a while ago, not because of the other girl (Jessica), and he feels guilty because he feels like he's betraying Lilly by opening his heart up to another girl. I tend to picture him saying to Lilly "I'll never love another woman," during their relationship, and feeling like a liar because it turned out not to be true. I don't feel bad for Lilly, she probably doesn't feel betrayed, and may even be happy for him that he is no longer hung up on her, his ex.