Ally is the one with the dyed black hair right? You established that her mother died in a flashback when talking about relationship with her dad. So who on Earth is this blonde woman suppose to be?
And Anne is suppose to be the Red-head right? I saw her mother alive in earlier comics.
Anne has naturally blond hair that she died black during her punk phase. She's also the one retelling her half of the story. The red-head is Lisa, who was the from the entire first half of Sunstone.
I think it's just that Alan doesn't know if Ally would be into that (not everyone who gives blowjobs enjoys getting a mouthful), and so he's erring on the side of caution, which is the decent thing to do. We don't know if Ally's ever done that before, but if so, maye she always had him finish outside.