I remember being a teenager and asking my mum how you know he's 'the one' whenever you find 'him'. I was so fed up of being hurt and feeling like I had to beg boyfriends to not cheat on me (ridiculous I even used to do that).
She told me that she knew because my Dad always stuck to his word. If he said he was going to be there, he was. If he said he was going to call, he would. He was always on time. Always telling the truth. It was always in the back of my mind that I was waiting for that person to come along.
When I went on my first 'date' with Warren, I was adamant I didn't want a relationship. So much so that I spent the whole time talking about my ex boyfriends in a bid to put him off. It didn't work because 6 years later we have two girls together and are getting married.
There wasn't a lightbulb moment where I thought he was 'the one'.. but there has also never been a moment where I have doubted it and I think that's how you know. It's cliche but it just kind of 'happens'. You don't need to question it or double check it, you just know.