What should I do if my bf is unsure about getting married one day?

Hi everyone, my bf is 22 and I’m 21. We’ve been together for 4½ years and have a good relationship. We don’t live together, no kids, we never really seriously talked about marriage until today after all these years.

I asked him about it and he said he is unsure about marriage and never really gave it a lot of thought. I was upset and he said he had no idea it was important to me. I told him when he knows for sure he doesn’t want to get married tell me and he said, “Why? You goin to break up with me?” and I told him maybe. I do know he wants kids when financially (he’s broke!) ready but there’s no way I’m having his kids if he won’t even marry me.

He said he honestly doesn’t understand marriage…what does it do for a relationship. Part of him thinks it’ll change our relationship for the worse. He is in the military, so marriage would definitely be a lot of help which is a plus.

He’s been very committed to me and he even told me I was his “life line” and I’m always there for him. He says his day can’t be normal without me and having someone to share his day with.