It is usually the child who does the dumping.

Well, "dumping" may be too strong a word. But in my experience, as my young friends grow up they usually wish to put aside childish things, of which their relationship with me is one.

Also, the attraction is not purely physical. Marriages are generally not doomed by the spouses' becoming old and wrinkly, either. If any of my little girls wished to remain close with me as they grew older, I would think this a wonderful thing.