I have been in a relationship with my boyfriend for 5 years.
Did you meet when you were 16?
I mean, sometimes a couple can't get married because the man isn't established yet and can't support a family. But in such cases, the man probably shouldn't have been "dating" if he wasn't ready to get married and start a family (which, for a Catholic, happens very close together).
The Catholic Church frowns on "long engagements". Dating is only for marriage, not for "having fun" or even, heaven forbid, fornication.
It certainly sounds like this boyfriend put the cart before the horse. He didn't even know himself well enough to know what vocation he is called to (marriage vs. a religious vocation), yet he has been monopolizing a woman during all that time.
Dating isn't just normal behavior that everyone does in the meantime. It is what an eligible young man does when he is ready to be married.
Even assuming no improprieties (e.g., fornication or other impurity) this relationship seems extremely disordered, from what you describe.