diff --git a/addon/adapters/application.js b/addon/adapters/application.js
index 9330c8f..fc7c9cb 100644
--- a/addon/adapters/application.js
+++ b/addon/adapters/application.js
@@ -196,12 +196,16 @@ export default Ember.Object.extend(FetchMixin, Evented, {
       return RSVP.Promise.resolve(null);
     }
     json = json || { data: { id: resource.get('id'), type: resource.get('type') } };
-    json.data.relationships = relationships;
+    let cleanup = Ember.K;
+    if (relationships) {
+      json.data.relationships = relationships;
+      cleanup = resource._resetRelationships.bind(resource);
+    }
     return this.fetch(url, {
       method: 'PATCH',
       body: JSON.stringify(json),
       update: true
-    });
+    }).then(cleanup);
   },
 
   /**
@@ -248,7 +252,7 @@ export default Ember.Object.extend(FetchMixin, Evented, {
     return this.fetch(this._urlForRelationship(resource, relationship), {
       method: 'POST',
       body: JSON.stringify(this.serializer.serializeRelationship(resource, relationship, id))
-    });
+    }).then(resource._resetRelationships.bind(resource));
   },
 
   /**
@@ -288,7 +292,7 @@ export default Ember.Object.extend(FetchMixin, Evented, {
     return this.fetch(this._urlForRelationship(resource, relationship), {
       method: 'PATCH',
       body: JSON.stringify(this.serializer.serializeRelationship(resource, relationship))
-    });
+    }).then(resource._resetRelationships.bind(resource));
   },
 
   /**
@@ -318,7 +322,7 @@ export default Ember.Object.extend(FetchMixin, Evented, {
     return this.fetch(this._urlForRelationship(resource, relationship), {
       method: 'DELETE',
       body: JSON.stringify(this.serializer.serializeRelationship(resource, relationship, id))
-    });
+    }).then(resource._resetRelationships.bind(resource));
   },
 
   /**
diff --git a/addon/models/resource.js b/addon/models/resource.js
index 534310d..43138bf 100644
--- a/addon/models/resource.js
+++ b/addon/models/resource.js
@@ -141,9 +141,11 @@ const Resource = Ember.Object.extend(ResourceOperationsMixin, {
     let existing;
     if (!Array.isArray(ids)) {
       existing = this.get(relationshipData).id;
-      this.removeRelationship(relation, existing);
-      if (isType('string', ids)) {
-        this.addRelationship(relation, ids);
+      if (ids === null || isType('string', ids) && existing !== ids) {
+        this.removeRelationship(relation, existing);
+        if (ids !== null) {
+          this.addRelationship(relation, ids);
+        }
       }
     } else {
       existing = this.get(relationshipData).map(function(rel) { return rel.id; });
@@ -245,9 +247,12 @@ const Resource = Ember.Object.extend(ResourceOperationsMixin, {
     let meta = this.relationMetadata(relation);
     setupRelationshipTracking.call(this, relation, meta.kind);
     let ref = this._relationships[relation];
+    let relationshipData = this.get(`relationships.${relation}.data`);
     if (meta && meta.kind === 'hasOne') {
-      ref.changed = identifier;
-      ref.previous = ref.previous || previous;
+      if (!relationshipData || relationshipData.id !== identifier.id) {
+        ref.changed = identifier;
+        ref.previous = ref.previous || previous;
+      }
     } else if (meta && meta.kind === 'hasMany') {
       let id = identifier.id;
       ref.removals = Ember.A(ref.removals.rejectBy('id', id));