Family control over Gf

I have been seeing my GF for 7 months and we enjoy one anothers company alot. She is ten yrs my senior and I am 61. She keeps my secretive to her sons as well as her grandchildren because i feel she is embarrassed by our age difference. She says her sons dont want the kids to be dissappointed as they were when they grew close to her last husband of 4 yrs. Another issue is sex. She is using her religious beliefs to avoid sex which makes it discomforting physically for her. advice please