Why hasn't my boyfriend of 6 years proposed yet?

I (27F) have been with my boyfriend (27M) for almost 7 years. We met when I was 20 and started dating on my 21st birthday, not that it matters. We moved in together about 2 years ago, discuss marriage/kids all the time, have the same goals, very rarely argue, and have a great overall relationship. So why hasn't he proposed? It's not a finance issue because he makes really great money. I cook, clean, do his laundry every week. He also does a lot for me and helps me around the house. He's a super romantic guy so he's always surprising me with flowers, trips, money, etc. He also has an amazing relationship with my family and my mom loves him so much. I don't really have a close relationship with his family, but he's never said this was an issue. We talk about marriage, starting a family and buying a home almost every day, but I wonder why he hasn't proposed. He knows I won't have a child or buy a home together until we're married. I've told him that I do not want to be a gf of 10 years, but at this point, I feel like I'm giving him an ultimatum.

Anyone have any insight or advice to offer?