Love. It's not about intensity, it's about consistency.

 She didn't fall in love with you because you remembered her birthday and bought her flowers on Valentine's Day. She fell in love with you because when you woke up in the morning you said, "Good morning"' to her before you checked your phone. She fell in love with you because when you went to the fridge to get yourself a drink, you got her one without even asking.

She fell in love with you because when you had an amazing day at work and she came home and she had a terrible day at work, you didn't say "Yeah, but let me tell you about my day." You sat and listened to her awful day and you didn't say a thing about your amazing day. This is why she fell in love with you.

I can't tell you exactly what day and it was no particular thing you did. It was the accumulation of all of those little things, that she woke up one day, and as if she pressed a button she goes, "I love him." And the same with the relationship, it's not about the events. It's not about intensity, it's about consistency.