To be honest, it's been 4 years, she's doing this, I think she's trying to push you into proposing to her. If I was in your situation, I'd say I felt really unloved because she doesn't want to express her love physically to you anymore, and it's hard to believe its for religious beliefs because of the past 4 years. To be honest, it sounds like somethings up with her, is there any chance she could be cheating on you? Either way, I don't think the situation sounds too good. Sit her down and find out the true reason to why she isn't doing it anymore, because I personally doubt its a religious thing because of the past four years, I think she either wants to get married, or break up with you. Women don't like the responsibility of being the bad one, so she'll make you dump her so she's the victim.