It's a question of time. Over time we learn who truly loves us, and who doesn't. Once, after 15 years of a loving relationship, my partner suddenly said he did not love me anymore and broke my heart. I really did not know why this happened. I loved him truly.
I waited. I gave him time. I did not pressure him or bother him. I kept myself to myself, and my love in a box in my heart. After about six months, he showed signs of getting close, then more signs, then more, so I let him in completely because he was sincere.
He had always loved me but something had happened (I still haven't asked what it was) and it had caused a rift in his love for me. He worked it out, inside himself.
We are together now 24 years and have an easy relationship with all the lines open.
Sometimes, things happen to people, unexplainable, which cause relationships to seems busted, but if there is love - in time, the relationship will heal because there is love. If love is not there, then it will fall apart - in time.