Some relationships end and some relationships should end. Often one or both parties feel injured.
If you want to end a relationship with two sighs of relief, pay close attention to what your “significant other” can’t tolerate in others. Perhaps it’s cigarette smoking. That is just an example of something I noticed a former boyfriend could not tolerate. When you are ready (IF you get ready) to end the relationship, instead of having a teary-eyed conversation with the other person, just do whatever s/he finds so very offensive that they will leave. You both will breathe a sigh of relief. You don’t really have to smoke (or whatever it is) that long. They seldom come back, but if they do . . . well, continue with your new bad habit and they’ll leave again.