Groups now only disband if all members reject the invitation (as opposed to if any member rejects the invitation).

Port From (https://github.com/TrinityCore/TrinityCore/commit/e3077813d5bf4521fff8be3ea24db231ed00c02f)

Source/Game/Entities/Player/Player.Groups.cs

@@ -253,11 +253,14 @@ namespace Game.Entities
 
             group.RemoveInvite(this);
 
-            if (group.GetMembersCount() <= 1)                       // group has just 1 member => disband
+            if (group.IsCreated())
             {
-                if (group.IsCreated())
+                if (group.GetMembersCount() <= 1) // group has just 1 member => disband
                     group.Disband(true);
-                else
+            }
+            else
+            {
+                if (group.GetInviteeCount() <= 1)
                     group.RemoveAllInvites();
             }
         }

Source/Game/Groups/Group.cs

@@ -2586,6 +2586,7 @@ namespace Game.Groups
         public List<MemberSlot> GetMemberSlots() { return m_memberSlots; }
         public GroupReference GetFirstMember() { return (GroupReference)m_memberMgr.GetFirst(); }
         public uint GetMembersCount() { return (uint)m_memberSlots.Count; }
+        public uint GetInviteeCount() { return (uint)m_invitees.Count; }
         public GroupFlags GetGroupFlags() { return m_groupFlags; }
 
         bool IsReadyCheckStarted() { return m_readyCheckStarted; }