I agree with you. In fact, I feel that this guy is trying to find an excuse to break up with the lady and he just asked your opinion to console his mind. That's all. I was never in a relationship but I can understand the psychology quite well. So, I think breaking up is the best solution at least for the lady.
I honestly doubt that his intentions has always been to break up with her.. It could be that the text messages he saw are what is giving him those thoughts.