So how are faith, hope, and love similar?

I thought they were together because they are the three things that remain, i.e. that are considered eternal. Although cynically, I'd say that theory does not necessary stand up to observed results.

Of the three, love is the greatest because it's given to others, not to yourself (or to God).

Put more simply: faith is given to God; hope is given to yourself; love is given to others...