It still boils down to whether you want to forgive them or not. If my husband does something thoughtless I appreciate an apology because it shows he's thinking of me. But if he doesn't apologize, oh well. I don't expect him to review every moment of his interactions with me to discover a slight and come confess his remorse. He's human, he'll do thoughtless things from time to time. Because I love him I forgive him whether he apologizes or not.

Were he to cheat on me, that's unforgivable. It really doesn't matter how much he apologizes, we're still getting a divorce.

An action between those two, something that hurt me enough I still love him but I'm not ready to forgive (can't think what, I'm pretty easy-going) that would require an apology plus some sort of action to convince me I should indeed forgive.

The only need for anything beyond acknowledgement of the error is because the wronged party doesn't want to forgive you yet. If you regularly require more than words from those around you then you may want to look at why you feel the need to hold on to slights so firmly. Either that or you have surrounded yourself with people you know aren't worthy of you to begin with and maybe you should stop saying you forgive them because you aren't actually forgiving them.