Leaving the Nest

I have a little sister, okay, not so little, she's in her early twenties, but she's always been the baby of the family (I have a total of three siblings). She's always been cute and cuddly even in her twenties and pretty much gets her way with everyone and we love her for it. That's not the point of this post though, the point is, when is love too much that it is suffocating? And how do you stop it from becoming like that and learn to let go?

My mother, who's in her sixties is desperately attached to my sister. She holds on to her with such tenacity that she has real problems letting her go and even though I think my sister is to blame for a big part of it, by always being the little baby because it granted her major privileges, now that she's trying to break out of the nest, my mother's psychological well being is hanging by a string.

The most recent of such issues is when my sister decided to take a trip to learn how to dive. Not only was mother trying to stop her from going on the trip altogether (which is really just an enjoyable relaxing beach trip in fantastic weather) she is adamant about her not diving, at all. No course, no diving instructors, nothing. Why do you ask? Because she really can't handle not seeing her everyday. She can't handle letting her go and admitting that she's all grown up, that she has a right to have fun and she can make her own choices. God forbid my sister decides to date a guy my mother doesn't like, seriously all hell with break lose.

When does love start to become suffocating? How can you prevent it from happening? How can you let go and know that your love is still the most important thing in someone else's life?