I think the saying is crap too. My brother talks to my mom (who lives 2 hours from him and 25 minutes from me) more than I do. He texts her every single night and chats about the day. He loves on her and adores her. He is in a serious long-term relationship, so it's not like he doesn't have a significant other. But he loves his mom. I also love my mom, but I am crazy-independent and can go for days without talking to her. We can relate on some regards, naturally. But I think that both of my brothers relate to her on similar levels. My dad is also very close to his mom. And one of his three sisters is totally out of the picture. She is flighty and flaky and doesn't really interact with her parents at all.
I do truly believe it has to do with your parenting and your children's personalities. Sure, some boys disappear a bit when they get married. But the same is true for some girls (my aunts two sons both live close to her and visit constantly, her daughter lives 500 miles away and they only see each other two times a year). I don't think there is an across the board on this one. You may have a daughter who hates you (sorry, it's true, for anyone!). You may have a son who thinks you hung the moon. Your daughter may be a transgender and decide to live as a man (happened to Cher). Your son might not marry and stay close to you his entire life. All of your kids could move 300 miles away.
There are no guarantees. It's all a gamble. A gamble of personalities and life experiences and relationships. I don't think that all-boy moms are doomed. At all. I think they are blessed in lots of ways. My grandma "gained" a daughter when my dad married my mom. My mom was motherless by the time she was 20. And my grandma totally stepped in and they love each other like biological mother-and-daughter. In fact, my moms MIL (my grandma) saw me be born :) And that was the only birth she experienced. Even though she has three daughters.
I guess I am lucky and have tons of real life examples of the variables of gender and how it plays out in families. I never truly feared not having a daughter. Sure, I wanted one (duh, otherwise I wouldn't be here and wouldn't have swayed). But I don't think I ever felt that my life would be less blessed without one. And I do think that these people who act like their daughters are the best, at the expense of their sons, created that dynamic. They pushed their sons aside and it became a self-fulfilling prophecy.
Sons are sons for life. Some are closer than others. But that is true no matter what.

