This is a topic I've been coming across a lot lately, so I thought I'd throw my two cents in. Being a woman, I will be speaking from a woman's perspective, but I believe this works for guys as well.
It seems that marriage has become less and less important in the past decade. People seem to think living together is enough, and even if they do end up marrying, they have likely been living together for some time already. Yet some people wonder why divorce rates have gone up in the last decade or so. Believe it or not, there is a correlation.
See, marriage is the result of love. Ladies, if this guy doesn't love you enough to commit to love you and be with you until death, why on EARTH would you give him your most precious possession? If he really loves you, he'll wait for you. If you want marriage, and he's pushing for intimacy before, then you can guess what it is he's interested in. Don't fall for it! If he tells you that if you love him you'll prove it, HE IS MANIPULATING YOU!!! You prove love by caring about someone, not by giving in to their demands.
Living together outside of marriage is not the result of love, it is the result of want. Even if the two people love each other, they are not living together because they want to spend their lives together. Some people say that marriage is only a piece of paper. If that is true, what's the big deal with actually getting married? If it's only a paper, what harm is it doing you?
I get that this might offend some readers, but I'm not going to apologize for it. So many people think marriage is a problem, and IT IS NOT. Marriage is an expression of love and devotion, commitment and promises. It is NOT an oppression of women, it is NOT a useless piece of paper. If you can't see yourself married to this person, leave him. If neither of you are willing to make the commitment to marry, then don't put everything you have on the table.
Fare thee well, friend!