What marriage means to me? Stability, Commitment in all its forms - emotionally psychologically. Security.
@Seesaworoundabout marriage is a contract. Literally nothing more than a legal arrangement. It doesn't bring stability, commitment or security. It just brings certain rights. (Which are not unimportant!)
The actual relationship you have with your partner, married or not, is what has the potential to bring you stability, security and emotional commitment. And joy and happiness and togetherness besides. All the really great things in life.
But, as things stand, you can't even talk about marriage with him (and I would guess, by extension, other difficult and contentious topics). What does that say about your relationship as it is right now?
I'm not saying LTB, by the way. I'm saying start with the relationship. Make sure you're committing to something and someone amazing. What you have right now sounds just a bit lonely and distant. A bit meh. Your first sentence literally reads: "I got engaged". Very lonely. And you keep referring to him as "he", not DP, not partner, not fiance. It really, really stands out. It's like "he" is not really there.
Finally, I have to ask, because they've become such a big thing, is it really a wedding you're eyeing up? Have a lot of your friends got married recently? Are your social media feeds full of wedding stuff? I might well be wrong here, just a thought!
EDIT: OP, I'm so sorry, I completely missed the really obvious bit where you say you're no longer pursuing marriage. I'll leave the post up anyway as relevant to the theme. Wishing you all the very best.