Chan e dubh a dh'fhuathaicheas, 's chan e geal a ghràdhaicheas.
Every hatred doesn't come from blackness and every love doesn't come from white.
I think this is a lovely proverb (in Scots Gaelic) which really shows that people's motives are what counts. Sometimes you have to be cruel to be kind to someone you love, even though it might earn you their eternal hatred or ingratitude.
On the other hand, love can be treacherous and false and shown for the wrong reasons. There are people who might see you as a steeping stone to somewhere else. Love can be feigned for money, for power, for status and for any number of ulterior motives.
On the other hand, you can kill someone with kindness and a surplus of love is nearly as bad.