I try domain access module for different domains. But when using user reference in contents every user sees other users. Is it possible to isolate every domain users from other domains users.
Use the References modules and enable user reference submodule.
Add a user reference field to your content. Then, in the "Views - Users that can be referenced" section of your field options select a View that filters users by current domain. You must create this view before add the field to see the view.