I, for one, have lost friends because they had children. I have some friends that are like family to me, who I will never give up on. However, more casual friends have blown it by having kids and then forcing them on me and my DH. For instance: I was friends with a married couple. When they had a baby, DH and I tried to deal with it, until this other couple invited themselves over to our apartment (baby and all). I thought this was rude and tacky...I don't want to baby-proof my apartment, I don't want it to get messy, and the thought of a diaper being changed under my roof is just too creepy and gross. I never did let them come over, and I haven't spoken to them since.