We both know

Not to brag, but let's talk about this straight then. Let's be honest. If we're going to do this, go for the real deal, complete with the labels, the obligations, the responsibilities, the caring, the boundaries, "really do this", I'll say to you, I'm probably going to give it 100% and more. When you need me to be there, I'll be there. I'll stand by your side. You need me to stay with you until the sun rises, I'll wait, I'll keep you company. But let me also tell you this. Before we begin, I know I'm going to give it this much and more, so I'd much rather not. We both know how this is going to end. It'll save me the trouble of regretting it later on when you don't reciprocate with the same level of commitment. It'll save us the trouble of wrecking this friendship.