Religion - Especially if you find a religious man/woman and you have the frame to keep them away from bad influences

Other than that, marriage is a ceremony/party if the law isnt involved and its a 'reward' for your family. Its a gift.

I emphasis the word 'ceremony/party', because once the law gets involved. Youre no longer married to each other, youre married to the law.

Also another bit of advice, if your SO doesnt care about having a lavish wedding, that requires a LOT OF money (that you could instead save for investing into your future together) and would rather just have a gather of friends and family, to celebrate the two of you. Then they are a keeper

Remember ya'll, keep the law out of it. The law only cares about what happens after the marriage and ensuring you pay, so they dont have to.

TL;DR - If your SO is more concerned about an expensive wedding or being legally married, over being labelled or 'seen' as married. They are not the one to marry.