Do we? I don’t know and I say nobody knows. It’s one of those existential questions in the same category as “what is the meaning of life?”. It’s healthy to ask oneself such things, but not to demand an answer.
If in doubt, turn left. It doesn’t matter where left is, it’s just not straight. When you question your own destiny then there’s something obstructing the view, so you need a new perspective, and to get it you just need to think out of the box and take another approach, hence turn left.
My roommate asked me that first question yesterday, and today this beautiful and sweet girl just out of a relationship posted on her Facebook wall “how many times can you fall in true love?”. To the second I answered once, and to both I replied “you’ll know you lived it when you’re living it”.
In the end those questions lead nowhere except to the proof that you’re depressed in some way. So just live what you have now and worry about the future you can provoke, take opportunities for what they are: a chance to make something great happen to you, and DO NOT hold back because you think you know what’s going to happen.
To close I’ll just say the following: don’t wait for that once-in-a-lifetime thing, because both death and true love both are one, but if you wait you won’t know which one will come first…