sex or marriage- Am in danger of losing him? I don't want to sin.

I am in a long distance relationship. We have been dating for about 10 months and see each other every 5-6 weeks. He is pressuring me for sex but as a christian woman i believe we must wait until we are married. He has been married before(I have not) and we are both in our early 50s. He is getting impatient about not having sex and thinks we should try eachother out before marriage. I believe it is a sin and I also don't think we have dated long enough to consider marriage. Am I at risk of losing him over this? Is sex such a big deal? I am not a virgin but i have asked God for forgiveness for my past transgressions. What happened to good old fashion morales?