In relationships there has to be compromises. Two individuals willing to except the other for who they are. Accepting the the person with their defects because no one is perfect. Willing to fight for them and stand by them no matter what. Being there and demonstrating what they mean in one's life. Making each other happy and not giving up when it seems like there's no way in continuing.
How can someone give up so easily, to let that person go that makes them into a better person. The one person they can be themselves with. The one that sees something in them that no one else does. Letting them go because little things can't be fixed or simply making it an excuse to hide the real reason. The fact that they now have someone they care and "love" for, that going any further is a fear and risk they are not willing to take. That they simply just end things. To not end up hurt and in reality just hurt the one person that accepts them for who they are and that loves them back but were too blinded to realize it.