Why am I good enough to be a live-in girlfriend or “fiancé”, but not good enough to be his Wife after 7 and a half years?

He asked me to marry him in 2017, but still won’t do it. I’ve presented him with dates, to which he will agree and then back out on. He says we gotta “work on stuff” or wait for this or wait for that. I ask him when we need to work on and he will never give me a direct answer. He says I’m good enough to be his Wife, but i believe his actions say otherwise, I’m 34 and he is 40. This is breaking my heart to pieces. He’s always agreed that marriage is important to him, but apparently not. I don’t deserve this and I just feel like I’m doing this to myself.