As you may know love can be war, people constantly fight for dignity and respect. It turns out that people can use very sophisticated psychological weapons to fight. Most of them are horrible, the idea is to control, humiliate and hurt the partner and "to teach them a good lesson". People want to be respected and loved back so often they think that they should be horrible because not many people can appreciate happiness in the purest form.
It turns out that the best way to avoid pain is to date an ethical vegetarian person. If they are unlikely to hurt an animal and cause pain, it is highly likely they will avoid playing any love games that will result in you suffering. If they cause you suffering, this is either because they are crazy [or a veggie impostor] or because they did it accidentally without realizing consequences. It is good to ask them about the intentions of something that caused you pain and suffering. You have to hope they are not lying.
Ethical veggie people have high moral standards and that is something of utmost importance. It is because prolonged hurting and despising has to lead to a break up or lack of love. IMHO only harmony in the long term can lead to long term success of relationship. I used to think that fights from time to time are healthy but now I don't think so, at least not for me. I think short separation to miss another person may do just fine as people tend to freak out when they are too happy. They create problems, when there are not problems and everything is fine. Good example of that is popularity of soap operas, some people lack problems so at least they live through problems of others. BTW. I hate soaps!
Mind you that there is actually an important difference between an ethical veggie and a person that is vegetarian for their own reasons [like health]. The ones that are veggies for health only do not count. This is because they are not altruistic in their choice.
It is important to remember that of course one does not have to be an ethical veggie and still not do all the horrible things I have mentioned. It is just that probability for an ethical veggie is lower to do all the messy stuff. A non ethical veggie has a higher probability to be more of an egoist in relationship than an altruist. Pure altruism does not work in love either, it is a marriage of both, but I would say a bit more altruism than egoism should be practiced.
Potential moral code of an ethical veggie [happens to be mine actually as well]: 1. I will not go to a party and photograph myself with all women except for the one I love just to show that person how much I don't give a F**k about them, 2. I will not try to despise another person to become superior over them, 3. I will not try to intentionally hurt them when they do action that does hurt me [war leads only to a war], 4. I will not consciously play on someone's feelings by making them jealous, which can be painful for them, 5. I will protect myself, my individuality and my beliefs but in a way to absolutely minimize suffering of the other person. Using WISDOM, diplomatic, calm, relaxed talk and silence as a support in that, 6. I will not lie to them to try to win something because I think lying is the only way, 7. I will not try to own and posses a person, a person is not a pet and pets deserve respect as well, 8. I will love a person like if it were a dog, a dog does not try to control the owner so a human being should never try to control another human being, dogs are the hardest to love because it may appear as they don't respect themselves. This is actually not true, dogs do selection who they love as well, and they love is not always required but they are submissive "to have a piece of mind". 9. If a human being enslaves themselves for us, it is because they trust us to know what we are doing but with the great power comes great responsibility, 10. I will doubt my actions as only a fool does not doubt what is right or wrong in such complex topic like human relations.