I've been there OP. My partner of 3.5 years lived with me for 3 years in my house. I wanted us to buy a house together, wanted commitment, wanted a family etc. We used to argue about it all the time.
He had nearly bought a house himself years before he met me, got so close that all his family and friends had bought him lots of homeware as house warming presents. He got cold feet and pulled out of the house. All of his homeware (pots & pans, knife set etc etc) stayed in their boxes at his mother's house even though he lived with me for 3 years - He never moved his stuff into mine in case he needed it for himself in the future.
He didn't even like committing to booking holidays together, because it made him twitch to book something a few months ahead...
On my 30th birthday, while chatting about a friend's wedding I said "well if we got married, we wouldn't do it like that". He replied "I'll never fucking marry you". On. my. 30th. birthday. And I still didn't kick him out.
Eventually, after another argument about commitment, he just walked away one day. I was 33, and devastated. My friends had been telling me to dump him for years - I never had the guts to do it. But it was the best thing that ever happened to me as I'm now with a wonderful man and very happy.
Ironically, I found my lovely DP via online dating.. and who else was on the same dating site..? My lovely commitment phobic ex. But he is still single, rents a house with his mates, has never committed to anything in his whole life.
Now I'm hoping your DP isn't as much of a pathological commitment phobe as my ex, but maybe you could examine your relationship and ask yourself does he commit to other stuff? Does he talk about future plans with you? Does he make more plans with his mates than he does with you? does he have boxes of homeware at his mothers in case he needs it himself, no surely nobody else is that fucked up Does he make you happy?? How would he react if you sat him down, and told him your hopes and dreams for the future?
Sorry this has turned into a rant about my commitment phobic ex, I think I needed to vent! Good luck OP