Best bet is, ask her. Not in a challenging way, in a genuinely curious way, open to whatever she might say.
I don't think her being a girlfriend versus wife is an issue unless she is religious and doesn't believe in sex before marriage. I agree, you need to give us more info here.
because she is your girl frend not wife
Samantha, we need a little more information. Usually though when dating and a major need is not being met, it is best to move on. With no other information than you've given, that would be my advice to you. good luck