falling out of love

my significant other of four years told me yesterday that he is not in love with me anymore, and asked me to move out of the house that we designed and built together, so i packed up my things and moved back in with my parents.

the heartache is unbearable and it’s got me questioning what is so wrong with me that the man who asked me to marry him just stopped loving me???

any advice for how to move on and get through something so heart-wrenching would be lovely