In a covalent bond they share the electron. H₂ is the perfect example of such a perfect sharing of electrons.

No their not sharing it, you can think of their attraction as simple an electrostatic attraction to a first approximation.

How do you determine beforehand what bonds are going to be ionic or covalent in a reaction?

So nonsimilars form ionic?

Gotcha, so thats why covalent bonds are stronger. In covalent, both atoms are latched onto those poor electrons for dear life, where in an ionic bond, they just like being around each other like opposite pole magnets.

Well.. u cant guage covalent bond stronger based on e nature of the bond..

I never heard of such generalisation. Perhaps it's a misconception raised from the fact that most covalent compounds have lower melting point than their ionic counterparts. It must be noted that melting involves breaking the strong electrostatic attraction between the ions in ionic compound and in the case of simple covalent molecules, it's just overcoming Van Der Waals' forces, London forces, Hydrogen bonding (any form of inter-molecular bonding).