selfishness, hmm. i don't know, i personally really enjoy seeing my SO having the time of her life. it was a huge turn on to see her unable to contain herself.
she would always make sure i finished though, regardless of how good she was doing. i definitely put her needs above mine though, for the most part at least. always going to be a couple times that your labido's just going through the roof and you need to clear some of it up and have to jump them in the shower