The scriptPubKey represents the conditions under which this output can be spent in the input of a new transaction. In most cases, it just contains a representation of the address owning that output, meaning that it can only be spent by a transaction signed by the private key corresponding to that address.
On your above statement , lets say address "A " has 5 coins or asset and "A" sends 2 coin to address "B" then now owner of 2 coins out of 5 coins is "B" so scriptPubKey contain address of B who is new owner of asset?
and in this case 3 coins which is unspent that will revert back to sender that would be unspent transaction output is it?