If your GF thinks its degrading then you reinforced those thoughts and emotions by your actions. Dating and everything else comes down to psychology, and in return you need to be a master in order to receive the results you desire. The other option is doing what 99% of the idiots do and is "leaving" it up to chance. You can argue all you want but if you can use sales psychology principles on her then you can make her want to do anything to you, even a 3 way with her sister if you were that good.