Your relatives residing with you are covered, such as your spouse or domestic partner, as well as your children are included.
Roommates are not covered under your policy. It is recommended for them to create their own policy -- invite them and you all will earn a free month of coverage.
Also, your fiancé/fiancée (and any other non-spouse, non-domestic partner significant others) are not automatically covered, you can change that by clicking the Edit Policy link underneath the policy in your dashboard.
See your policy for full details on your exact coverage.