There can be a lot of pressure from the outside on your relationship from different aspects of your life. Whether it is your family or your friends you should know how to handle that type of situation and recognize it before it comes between you. Put on a united front to deal with outside pressures and they will not take you down.
Friends
Sometimes the friends you have may not get along with your partner and that is okay. You may talk to your partner about this to see which friends they do not like. Once you have established this you can make plans with them outside the relationship. If your friend is trying to damage your relationship by suggesting you do things to upset your partner then you should probably consider taking sometime apart from that friend.
Family
Family can be a little hard to deal with. They may give you unsolicited advice about your relationship that you feel is none of their business. You have to smile through it and try to see that they are trying to help instead of taking it personally. If you are not careful a simple suggestion can quickly escalate into a fight between your partner and you. Make sure you talk about anything that bothers you right away instead of dreading family visits in silence.
Time
Whether you are able to spend a lot of time together or not can be an outside pressure on your relationship. You may have long hours at work or you may not realize you are having out with friends more than them. This can become a problem over time if you do not make time to be together. Make sure that you use your time wisely and that you are making the most out of the time you do have together. While these outside pressures are uncontrollable you can control how you react to them, and the best thing to do is just roll with the punches.