The most painful word in the world? It's CATHECT. Dictionary.com (Subscribe to its "word of the day"!) defines it like this: cathect kuh-THEKT, verb: To invest emotion or feeling in an idea, object, or another person.
Why is it so painful? Because as soon as we invest emotion, as soon as we start feeling, we're opening ourselves up to hurt. When we don't feel, there's no pain. For many, it's a viable option. The problem with not allowing ourselves to not feel is that it's not just pain that we eliminate from our lives. It's joy, too.
If you love someone there's going to be pain. Pain when they're hurting. Pain when they hurt us. Pain when they're away from us. But the flipside is the potential for great joy. Joy when they succeed. Joy when they please us. Joy when they're with us.
Two options: A painless yet joyless life, or a life loaded with both ache and bliss. You choose.