Student or Learner
I am not sure if my sentences sound natural. Would you please correct my mistakes?
John could not talk freely with his girlfriend because of the barman who was putting bottles on the shelves nearby. He knew he was listening to their conversation, although he pretended not to.
I would change "he pretended not to" to "he pretended he wasn't."
I would probably add a comma after "barman" (and I'd used "bartender" because I'm an American).
There is no confusion for me knowing which "he" is "he."
John knew the bartender was listening, although the the bartender pretended he wasn't.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.