This will probably sound like old news but take some time and take some space from your partner. Go do a couple of nice things on your own (massage, intense workout, nice dinner, a day hike). You may find that you miss the person's company afterwards or appreciate them a little more after you've been able to breathe on your own.

Also, it's extremely important to talk to you significant other and make them aware that you're feeling this way and help them to understand that it is related to your own feelings and not their personality. This will help them to give you what you need.

Personally, I've ended several relationships while low and gone on to realize that the person may have helped me get through it or at least been a great person for me if I could rebound.

Also, don't feel bad. It's awesome that you haven't made the rash decision already. Being able to reach out and think it through is something to be proud of. I'm still just trying to work up to that myself.