Do you believe in the philosophy that your first love will lead to your first heart break?

Not a philosophy but, unless you may and stay with your first love, a fact.
It's all just practise, learning what's required to stay in love

Well.... there’s puppy love and then there is bonding.

Puppy love will always lead to heart break.

Of course not. That is too deterministic. But you are right it is messed-up thinking ... and self-fulfilling.

My first love turned me into a relationship hating man-whore

I thank her a lot 😂

Not necessarily.. a lot of people have married their first loves

Depends on you're self-worth.