So happy that things are going so well for you Aurelie. I think it's fantastic that the four of you are starting to form a close unit. It's especially good seeing that it is Nathan that is the driving force behind it. He must be a very mature and confident young man. It must be lovely for you to see your son and your lover start to bond a little by kissing and hugging when he dropped him home that time. I think it's made even more special by the fact that Nathan is encouraging this relationship to form between the two of them. He must love you very much.
How uncomfortable are you with allowing Nathan to watch you having sex with your lover. I dont think you should feel forced into doing something you dont want to do, going by Nathans posts though, I dont think he would ever want you to do that. If your just a bit unsure about it and it's something he really wants I think you should at least try it for him. If you or either of your men dont like it, you dont need to do it again.