Do i have to know the pc password to vpn a computer?

depends if there is no local admin password or he know it,

For instance your boyfriend has a log in name "Tom" and you have a log in name called "Jane" your passwords a diff so in that case he cant see access your files but built into machines there is a user called Administrator (most of the time they are disable epically in home edition and basic if you are running windows Linux its called root which is not disabled) and if he knows or there is no password he might be able to get in