I believe in pixies. The little pests frequently hide my tools when I am working. I can even strain myself and believe in an honest politician. But unconditional love does not exist, nor should it.
Use the romance addled mush between your ears and think about it for a second. Unconditional - you love him no matter what. Ain't gonna happen. Everyone has boundaries beyond which they can't go. It's part of being human. Way down deep we protect ourselves, even from ourselves.
I am not talking about abuse either. What if he cheats on you? Still going to love him and accept him then? Maybe he kills someone - is that totally fine with you? Maybe he'll turn into a cold and uncaring father. You pick him over your kids?
See the irony in your question now? You believe in it, yet you are already putting conditions on it to protect yourself.
Now I done shouting at you over semantics and muddy thinking though ....
Love just is. How you feel for him now is pretty much how you will feel after you get married, and for a lot of years thereafter. Yes, love grows, gets stronger and deeper over time, but it is a very slow thing. Loving means risking hurt because you trust the person.
He probably is worthy of your trust.