How do I know I should break up with my boyfriend or girlfriend?

If you aren't happy in your relationship, there's a red flag already. Being happy is the most important thing, and if being with a certain person doesn't do it for you, then you are in no obligation to stay with them. If you feel as if there's a rough patch you just can't get by or you can't compromise something, then staying in the relationship could be toxic for both of you.

When you realised that respect has gone between both of you and know one have respect for the other one.

You know if you look at the relationship and you realize that it doesn't make you happy anymore. Relationships are the connection of two people over time and sometimes time can make it so that that connection is no longer very satisfying for you. If you look at the person, or at your relationship with that person, and realize that it's not benefitting you or your happiness, it might be time to put some distance. That's not to say of course that there aren't hard times where the relationship won't make you happy. Those do happen, but it's about whether over time they are still making you happy or not. Look at the recent past - have things been going well? Is this just a rough patch? How long have you not been happy for? Ultimately, it is your decision and you know what's best for you, but take a look at the whole picture. Are you okay with the relationship? That will help you decide the best course of action.

Usually if you are asking the question then you are ready to make that break. It can helpful to have a conversation with your boyfriend or girlfriend about what might be troubling you. Be honest and be kind breaking up can be painful for both parties even if it is the right choice to move on.

A relationship is a tricky process, its when you work together as a team and you are each others best friends. Make sure that you guys are doing things equally for each other and with each other.

if you are not comfortable anymore with her/him. and you feel that s/he is not the one you loved or they are not worth it anymore :)

You probably already know the answer to this. You should only be with someone you feel good with all the time.

I think this is a very personal question. I personally would breakup with my boyfriend if he cheated on me. But how I said it is different to every relationship.

If you feel that your relationship with your boyfriend/girlfriend just isn't healthy anymore or you aren't happy with them, think about everything that you've been through with them and if the relationship is still worth it to you anymore.

If your gut is telling you to, then do it. From experience, as soon as you question whether or not you should stay together, then you should leave.