what does it mean when he says he doesn't want to break up but he is not sure if he loves you anymore?

Love is easily one of the most complicated and difficult emotions to process and express. The fact that he doesn't want to break up likely stems from a desire not to throw something away while he is still uncertain about his own feelings. It could also be that he is afraid to be alone; the truth is nobody can really know the mind of another. The only way to know for sure is to ask.

It means he wants you to stick around so he can use you as a replacement... Or he probably wants to be friends with benefits

It could mean that he is going through his own issues and needs some time off. It is not a reflection on you but his own internal conflicts.

if he doesn't say he loves you, maybe you could try to work on repairing your relationship with him. remember not to depend on a boy to make you happy.

From personal experience, if I cannot love someone anymore, but I don't want to leave the relationships, that means I am still with them because of the sense of comfort that instilled between us. It is not easy to leave a relationship in which you perhaps built so many things, but my sincere recommendation is to simply face the truth. Continuing with the relationship would only hurt both parties. Instead, a clean break up might be the solution - life goes on, after all.

His head may be a little all over the place. Allow him some time to think about what he wants, but in that time also take it and use it to think about what you want

It means he does want to break up but he doesn't want to hurt your feelings. He wants to let you down slowly but doesn't know how.

This seems like quite the confusing sentence to have to hear. I would think that he himself is unsure of his feelings towards you, but also that he wants to keep you close in case his mind is wrong in its thoughts. Talk to him about how you both feel, and where you would want your relationship to go from that point.

Choose to leave. It is hurtful but when someone has their doubt, then it means he doesn't love you enough to want to fix things. People do fall out of love but they always find ways to fall back in love with their partners. There is no point keeping someone who doesn't love you or make the effort to fall back in love with you. Dragging a relationship that way will just make matter worse.

Has something in your lives changed recently? Is he able to pinpoint it? If he is having doubts it might be best for you to try seeing other people so that you could both figure out what you want. Breaking up with someone you loved and might still love is very difficult and scary but if you both really love each other you will find your way back to each other. I think what he means is that he is confused, it is a good sign of your relationship that he feels comfortable enough to share his feelings with you. I would try asking him what he means by he's not sure that he still loves you. He is probably the only one who can actually clarify his meaning.