He is adamant about breaking up

My boyfriend recently told me that he has fallen out of love with me, after a year-and-a-half of dating. He said there were many signs and that he had repeatedly told me things were not going well between us, but I didn’t do anything to fix them. I know he mentioned this before, so it wasn’t a surprise to me, but I think a part of me always believed we could work things out and that it wasn’t so serious. He wants to break up and nothing I say can convince him. I don’t know what to do. I agree with everything he says and know things are bad, but I also believe we can work through these issues if he gives me a chance. I don’t want to lose him. What can I do?
If he has mentioned this before and it hasn’t come as a surprise, doesn’t that mean the chances have already been given? It’s possible that you both have a different perspective on the seriousness of these issues, but a relationship can’t function with just one person trying to bring about change. You can tell him that you believe this can be resolved, but if it has reached a point where he doesn’t see a way out, you may simply have to accept that this relationship is over. It may sound harsh, but everyone has a different breaking point or red line, and it sounds as if he has reached his. All you can do is hope that he wants to try again or accept that he is ready to move on.

Should I stay with my fiancé even if I love someone else? We were engaged after a short courtship when I didn’t know if I would meet someone more compatible.
If you don’t want to commit to a lifelong relationship with this person, not speaking up is harmful to you as well as their future. Marriage isn’t something that should be endured, because it is unfair to you both.