Why would you put her in these situations when you fuck her mouth?
a. Because her girlfriend was't around to restrain her and you can't do two things at once.
b. Because when you're done blowing a load down her throat you might want to come back and take another shot at her slut mouth.
c. Because when you're done you want to get some friend and show them what you did.
but best of all...
d. Because it turns her on.