Oh man, have I got a treat for you.
THE entity I use to bring that feeling of relief and compassion to people is Nachliel.
This bad boy is a literal master of bringing about relief and release from pain. He eases emotional pain, and his compassion is actually quite overwhelming at times.
I called on him for different cases (such as friends going through tough shit), where emotional pain was involved. I am sure he can help you out with a breakup.
Another angel that you can call on is Orpaniel. He is a very relationship oriented angel - he can heal a relationship that is damaged (but works best when the relationship is actually good underneath it all), and also ease that awful pain from breaking up.
Suffering, feeling of loss, guilt, regret - he will heal all of this.
As for demonic spirits, as Sarah pointed out, Lilith is probably a good choice. I’ve heard that she can be rough at times, but also unbelievably compassionate and loving. I am sure she can help a person get through that pain of breaking up.
Hope this helps. 
I’ve found that some spirits just have some quality that you inherently admire and want to learn more from them, or you just like them for some reason. Quite fascinating indeed.