Take control of your relationship, first and foremost. Often the girlfriend doesn't respect you or the relationship because there is no control, no leadership, no determination, in the relationship. You worked hard to get this girl and now you have her, some stuff may have happened but now you're in this gray zone where you're friends, essentially, but you're just playing the role of being a boyfriend, instead of really being one. Once you've stopped working at the relationship, you stop dating her and take for granted that the relationship is there, the respect has gone out of the window.
Take control of your life, in general. If your life is full of chaos chances are your relationship will be as well. She may have respected you at first, in the beginning, then realized that none of your friends do, your mother doesn't, so on and so forth, so she falls into that same pattern of behavior. Women want someone that people take seriously, that have their own presence when they walk in a room, that have some authority! When they can't see that in your other relationships, unless they have come to know you in a different way and see a side to you that no one else does, chances are they won't respect you much either.
It sounds cliche, but a man who isn't serving God who doesn't have any clear direction won't have one for the relationship and will inevitably fall into a pattern of disrespect from his woman, and then his own children. You can't be the man of your house without realizing who really is at the head of your life.
Don't ask or demand respect, show it. If you are willing to drop everything for your boys or someone else and not your girlfriend you aren't going to get that respect, period. Respect your woman, show her how much you appreciate her and take interest and what interests her. It's nice when women have someone to be their cheerleader and show them some support, rather than for them to always do it for someone else. If you don't really believe or respect what she's doing and do not see any potential in her it isn't much of a relationship anyway. If the relationship is all about what you're doing that isn't going to last, and no one respects anyone that gives up their own goals and ambition to be in a relationship with someone without any type of plan whatsoever for their own life.
Date women that you respect; if you are dating simply on physical and sexual attraction the relationship is short lived, regardless of the chemistry. Getting respect in your relationship with your woman is no different than getting respect in any other area of your life. The problem is that if you come across as someone who doesn't earn respect, particularly if you're passive aggressive and like to take your respect from people at inopportune times, the odds of being respected within the relationships is that much less. Too often men will do what it takes to be with someone then wondering why they can't keep them, if they had to compromise, they already had to lay down the foundation for which they'll be disrespected later on in the relationship, and there isn't any going back at that point.
The best way to get someone to respect you is with your actions. Also, you must treat the person with the same respect you would like to receive. It will not happen over night. You will have to work for it. Take part in the chores and try to make life easy for you both. Be a real man and help out. Listen to your woman and try to meet her needs. If you can't do that then maybe you don't need respect. It is not something you just get for nothing. Nobody owes you any respect unless you have earned it. If you are a good boyfriend. If you have done everything to help your relationship and have not tried to hinder it. If you truly honored your promises and commitments and your woman still will not respect you, then you should find someone who will. You should be treated the way you want to be. If someone is not doing for you what you feel they should then go out and keep looking. People seem to find someone and then try to make them the way they want. When it does not work out they get upset. Try finding someone who has what you want already. It works way better. I don't know how someone could get into a relationship without mutual respect. Or maybe the respect was lost somewhere along the way. if so then why? In conclusion, if you are in a serious relationship with someone who does not respect you then you should find a new partner who respects you.