Struggling to break up with my girlfriend — feeling physically sick at the thought

I’ve been seeing a girl for about a year, we could call her my girlfriend. Lately, I’ve been having the thought that I want to break up. I just don’t see a future with her. I can’t fully explain why, I simply don’t feel it anymore. My attraction has decreased, but as a person and friend, I really like her. Our personalities are different, but she does so much for me, which is part of what makes this so hard.

The problem is, I’m completely unable to break up. Even thinking about it freezes me: I feel nauseous, I shake, I literally can’t do it. You could call it cowardice. I know I’m wasting her time, but the thought of seeing her hurt terrifies me.

We’ve talked before about things like our personality differences, for example, if I’m not in the mood for sex but she is, she experiences it as a huge tragedy. She can be strong-willed in other areas too, she wants to go on a vacation now, but I don’t, and she actually cries because of it.

In the present, I feel okay with her most of the time, but I can’t see a future, and it shows in our daily life. This isn’t really a question of whether I should break up I already know the answer. My real question is how do I stop being so afraid? The very thought of breaking up triggers physical symptoms. Last time we discussed these issues, she cried, and I felt horrible intense guilt, freezing, nausea, shaking.

I feel like this fear is preventing me from asserting my own will, and it’s exhausting me. How do I overcome this paralysis and actually take the step I know I need to?