Okay, here’s advice from an engaged 20-year-old, so take it or leave it as one of experience or inexperience 😀 First of all, financial independence. Yes we are 20, and yes I am in school, but FH is military and has his own income, while I have been financially independent outside of housing/tuition for four years (paying for all expenses outside of my tuition and everything out of my own house in high school). You need to know how to deal with money. Do not rely on him – build your own credit, have your own savings, etc. And if you show your parents that you are capable, as a couple, of supporting yourselves and even willing and able to take on all aspects of your life, that can help a lot. In my case, we talked through every expense we could think of and compared it to our own salaries to see whether we could truly live on our own (tuition, fees, books, rent, food, transportation etc) We determined that it would be difficult, but we could do it. Then we "presented" our plan to our parents, who assured us that they were willing to continue contribution to my tuition. Financial maturity is usually one of the greatest concerns – they don’t want you to get married then, years later, end up divorced with no credit and no savings.
Your relationship, of course, is also important. Are your parents aware of your commitment to each other? Do they know that you have talked through every scenario – maybe even bought one of those marriage advice books and gone through the little quizzes and questionnaires? How many (if any) children, what religion, will anyone stay home with children and who, what kind of professions will you have and will that restrict where you live – and where do you want to live? Can you compromise and live happily if he loves the country and you love the city? I think these are the kinds of things your parents are worried about and if you can let them see that you are prepared and mature – like anyone else getting married but you just happen to be younger – it may ease their fears.
Also, just be prepared for criticism of your choice. Take it and let it go, because if you hang on to it, or appear defensive, it will only increase the doubt in other’s eyes and perhaps instill doubt in yourself (though if you do have this doubt, and your parents’ disapproval might be bringing it to light, let it come through – talk about it with your fiance and a good friend, and be sure that this is the right choice for YOU forever). You should recognize, also, that truly many young marriages do not work and people are going to think of this first when you tell them. However, many older marriages do not work as well -if you are not honest and open with your partner, especially. My mother said this to me when I first brought up the possibility of my engagement with her: She married my dad in her early 30’s and (I am oversimplifying) let him take her along for the ride for years, allowing him to push her around, while neither of them expressed their true feelings out of fear for hurting the other. They were divorced after 17 years of marriage. So, marriage does not work for many reasons – not just because you are young.
Even some of my "best" friends were stand-offish at first towards me. Generally as a culture we don’t expect people to marry so young and if it happens, it makes people around you feel like "how is this happening already?" I talked to my friends more later, and they explained that they were just kind of shocked that we have grown up and this is a possibility – then proceeded to apologize for being distant and telling me how they just knew it would happen with me/us (these are the people who told me "you are going to be married first" in middle school). Your parents see you as their child. It is difficult to accept.
(Sorry I wrote so much! It is important to me that if anyone is planning on marrying young they are not just dismissed with the words "it won’t work" or "why would you do that". Neither of those are constructive and neither will change the person’s mind. Only he or she, at this point, can and will make the decision, and I hope it is based on careful thought and analysis of what is best – whether that is to keep dating, to live together, to become domestic partners, to marry, or even to break up – whatever is best for them PERSONALLY and not just their relationship in the long-run)