In my oppinion Anakin should've always been a ladies man. The way I envision Luke and, Leia's mom was that she was just a worker for the Queen (on Alderaan) that was one of many woman Anakin slept with. Then during an attack on the place she can only get one kid(by this time the kids are like two years old). She gets Luke but, Leia's off elsewhere. She flees with Obiwan to Degobah. (She and Obiwan were friends prior to Anakin and, Obiwan's friendship) With Owen and, Beru they all flee to Degobah. Tragically the mom suffered an injury during the attack and, died. Fearfull for tramatizing memories Yoda absolves Luke of the memory of his Mom. Luke, Ben, Owen, and Beru go to Tattooine (a place not seen 'till this moment) to hide. The Queen finds Leia takes her as her own.

...As for fitting those events into three films... I don't know just wanted to post my idea for Luke and, Leia's Mom.

Also for the most part Anakin and, Luke & Leia's Mom don't speak to eachother after they spent the night together. It was mainly just a one night stand.