If you two are headed for marriage, then you two need to get started with the hard work of preparing for marriage. NOT planning your wedding -- preparing for a lifetime commitment to mutual support, mutual respect. If two aren't ready to go over each other's finances together every week (pay stubs, saving and checking accounts, credit card bills, cash receipts), to spend a lot of time with each other's families and pitch in with the family responsibilities of each other's families, to work out "rules of the house" like whether people can just drop in or need to call first, whether it's necessary to check with your partner before inviting people over, and so on. It's not the bended knee and ring thing that tells you your sweetheart is serious about marriage, ready for marriage -- it's the years of hard work in which the couple determines "Now that we're sure we WANT to get married, we need to know whether this marriage would be happy and lasting, need to know whether there are fundamental differences that would get in the way of the marriage working."
Along with that, please don't try to have it both ways. I find it laughably ridiculous when a pair has determined to marry, is exclusive, socializes as if they were a couple, expects to be invited together like a couple, expects to be recognized as "significant other" rather than mere boyfriend-girlfriend -- but insists "We're NOT engaged." If you're not married or engaged, then you're SINGLE. If you want to be regarded as a couple, then BECOME a couple -- get engaged.