they just have to have experienced True Forgiveness recently.
Recent vs current, or even how long 'recent' lasts, and what might bring it to a sudden end, is not well established.
Dresden didn't lose the protection his True Love afforded him because he fell out of love, but because he engaged in intimate acts with someone not party to that (possibly former) exchange.
And for a +0 Catch, erring on the side of exclusivity should not be unreasonable.