I have two nitpicks with this, I think line two in the first stanza should read:
'there are a few hurtful words'
which is minor, and I'd like to see this without the upper-case at the beginning of each line, though that is most likely just me and I ought to be ignored.
I like yor title and how it relates to this, it's simple, a simple concept simply written and all the stronger for that, I think. You let your words do the talking, there's a lightness to this which I thoroughly enjoyed.
I like your questions, too, the uncertainty, which adds strength to your certain ending, a weight, you know? A good weight, I mean- the change from uncertainty to certainty, something about you letting us question, too, and taking us round this circle with you, that makes me feel your ending more. And that afar is a lovely insert :)
'We believe in us, but fights give us doubts'- this is so true, its awful how a fight can really make you hate a partner, even while you love them, how you end up saying things you don't mean and wish later that you could take them back, and really, god, it's awful after, I always feel so guilty about the things I say when I'm fighting, with anyone, really, and it does lead to doubts, but only in that moment, and then they pass and their smile, yes, it is enough :)