My question is why are going to feel bad? about taking that step.
Why? Because you'll no longer have someone. If that's the case, understand what is known to the rest of the world.....there is more fish in the sea, per se.
If you're the reason for ending, because of something you did? If so, then accept it and move on.
If you're reason is because of what your partner did? Then, figure out if you can live with it and still remain with them. If you cannot, then you should not feel bad about it.
See, my above question- Why?