If you are someone who has thought of loving the one who has a broken heart. Let me appreciate you first, as far as I have seen, it takes a very strong man/woman to do what you are thinking of. Not everyone is strong enough to do it. It can even break you down because what the other person is going through is an emotional break down and it doesn't necessarily have to be someone with a failed relation, there are other circumstances for example parents divorce, death of someone very important, career crisis, failed marriage anything that takes away ones faith from love, humanity or even self. Here are the basic things you need to understand if you want to stick to what you have thought.
1. Negativity:
This phase may be outcome of above stated circumstances or anything else that led to him/her to this. The person is engulfed in negative aura and will engulf anyone who comes near. You need to buckle up your boots to not add on to the negativity by blaming them, or telling them that it is their fault, or telling them what they should have done. You need to understand that even you have to look forward in order to make them think differently rather then being stuck in what could have been done, what must be done now is more important. Take your daily dose of positivity and carry some extra for them too. The aura may not vanish but with time it will decrease.
2. Patience:
You need to understand that they keep repeating whatever they said again and again to an extent that they get tired of it themselves but cannot help not doing so. It is just a phase that they will come out of it on their own but right now they really need to take it out especially if she is a woman/girl. The best help you can give is by being there if you cannot make them look forward, be there until they takeout every last bit of the reason why it hurts. The better they take it out the sooner they heal and are able to move one. They will feel much better. This will be hard for you because at times they just won't open up crediting to their experiences and it might actually take forever for it to happen. They will not make sense in this phase so you really need to have patience with them. You should understand that they aren't just going to be normal the other day and start loving you, it will take time to over come all the hurt, the insecurities to start again even if it is with the same person or new. This insecurities stay long even after he/she has started loving you, that is why you need to keep assuring her. It takes a strong person to actually hold on to a broken heart.
3. Assurance:
In this phase all they end up doing is directing all the negativity towards themselves and end up feeling worse. You need to provide constant assurance that she/he is more than what they think they are. Keep reminding them of all the good attributes about them, their achievements, keep assuring them that they will make through it. Make them feel good about themselves, encourage them, tell them there is something better waiting for them, read them motivating quotes, let them read on similar experiences shared by others so that they know they aren't the only one suffering (but do not tell them this let them understand it on their own). People everywhere are actually suffering from one thing or another. Assure that there are people who will never leave, like you or their family, close friends and let them know how much they mean to you all.
4. Love:
Here, loving will be so much difficult as you know that they are like empty cups and in order to fill them you have to fill them and on other hand you end up getting empty. So you need to take time for yourself to fill yourself and give them again. You cannot run away at this point, they really need you though they themselves never tell you because they don't even realize that at this moment. Its hard to make them trust someone new after what they have went through, or bring back faith in love, life or themselves when they have seen their world crashing in front of them. It will take time and a strong determination. You are at the opening and they are in dark pit, some grab your hand and come out some just do not and you have to wait way longer then you thought. You might want to give up at a point where you keep feeling like you are the only one loving but before giving up do think why you were here in the first place, this is the time they need you the most.
5. Stay strong:
You have to be this strong savior because you never know when they are going to break down, or when they get anxiety attacks and just start being scared or just have an emotional outburst. They never mean to do that on their own it just happens. So you need to be strong for them as well.
6. Acceptance:
Acceptance gives them motivation to come back to their real self. Do not judge them for what was there in their past. Let them talk about it just hear when they tell with no judgement. If you cannot accept them with their past I strongly suggest you not to come in their life, someone who will accept them fully will come sooner or later because when you cannot accept them they will end up getting more hurt in future. They have already suffered so don't hold their hand if you are going to leave them in mid way.
7. Help in disguise:
Reach your hand out for help only when you really mean it because when you do show that you are actually trying to help them or do them a favor, may make them feel like a burden to you and might resist all the help and support and never come out of it. So be there without trying to prove that you are there because they need to be saved.
8. Expectation:
What hurts the most is you expecting them to love you back, to give back when they are in this phase, they surely will once out of it but they just want to be loved, to be cared for, treated well when they were made to feel unworthy by someone else. Try to understand them, they might push you away or may be cling on to you too much. Keep the level of expectation to the minimum.
They will love when they heal, do not force them or expect that all that you put in will show results at times it takes way to long.