My love for my husband has been a gradual thing. I had an instant desire and fondness for him. Even felt love for him after time. But the deepness of the love I have for him has really only intensified over the years and all the things we've done together and been through. I know after I gave birth to our first daughter I looked up at him and saw tears in his eyes and I was overcome with love. But I can't give a specific time when I just knew.
I thought I knew in high school when I was around my SO I was full of butterflies. Years later, I knew it was "forever" when I saw my daughter trying to climb his leg while he was doing dishes and he looked half amused, half annoyed and I just thought "this is my family...this is how it is supposed to be...this is as good as it gets". It was just a cute little morning moment where everything felt really normal and natural and right.
As I was getting to know my "husband" as friends when we first met I could feel myself falling in love with him. When I told him I had a daughter from a previous marriage, he wanted to meet her so we arranged a "date" at the mall. So the three of us got together at the mall so she (just under 2 years old) and he could be introduced. As we were walking down the mall she grabbed a hold of his hand and held it tight as we walked along. He looked surprised and then smiled at her and held his head high in pride. I saw it all and knew it was pure love from that moment on. We've been together for over 18 years and just celebrated our 16th anniversary. I love him more each day and she is still his "little girl" to this day.
I don't know but I do know that I fall in love all over again every time I see him playing with our daughter, feeding her, holding her. Like the previous poster said, this is my family and it's amazing.