Why won’t my (25F) boyfriend (27M) propose?

We have been together for over two years. We moved into a house together (which is only under his name) and we have been doing projects on it together for a year. We got a dog together. We’ve been on multiple trips. Whenever the conversation comes up, he says he is just scared because the men at work tell him to never get married and women are gold diggers. I’ve said many times I have no problem signing a prenup. He brings up kids and I remind him I will only have kids if we are married. It seems like he wants a future but there is no intention of acting on it. I feel I’ve proven myself and I’m committed, so his hesitation is starting to make me question if he is actually as committed as he says. How do I know I’m not just a placeholder until the one he really wants comes along? I don’t feel secure since he won’t commit. I feel like the rug can be pulled at any moment.