To be or not to be?

My bf of 11 months has changed his opinion on marriage. I’ve always wanted to get married but these past few years have changed my views. I realized I don’t have to be married to be happy and I’m not sure I want to marry anytime soon at least. My bf was strongly against marriage in the beginning, however now all of a sudden he wants to get married and has even asked me to pick a ring with him. I don’t want to tell him a hard no but I also want to know why he changed his mind? I’ve asked multiple different ways why he wants to marry now but he just says he changed his mind and if he gets married he wants to marry me. I feel like he only wants to marry me to keep me permanently and he only wants that because it’s what I want. Is it bad I don’t want to get married because it’s what I want but I need him to want it as well? If he randomly proposes I’m not sure what to do.