It's true that BPD symptoms are often exacerbated by certain situations, people, or events. For example, many people with BPD find that their symptoms are triggered by criticism by loved ones, reminders of traumatic events, or perceived episodes of abandonment or rejection.
One strategy you can use to manage BPD symptoms is to avoid triggers altogether. However, you need to exercise this strategy in moderation. Avoiding triggers can be very helpful when the trigger you are avoiding is predictable and avoiding it does not limit your life in significant ways. But, if the trigger is unpredictable, or involves very large domains in your life, avoiding it is not a good idea.
For example, many people with BPD are triggered by conflict in their relationships. However, the only way to avoid conflict in relationships completely is to have no relationships at all (since conflict is an inevitable part of all relationships). Unfortunately, many people with BPD find themselves doing this -- they may become avoidant of relationships altogether in order to avoid exacerbating their symptoms. But, of course, this strategy just intensifies feelings of emptiness and loneliness.
If a trigger is more limited, however, it may be just fine to avoid it. For example, if you know that you are triggered by movie scenes that are reminiscent of a traumatic event, or by a particular sad song that reminds you of a breakup, you can avoid the trigger without disrupting your life.
When you are deciding how to manage a trigger, ask yourself whether avoiding that trigger will disrupt your life in some way. Will it get in the way of your ability to work, engage in relationships, go to school, or enjoy your hobbies? If the answer is yes, find another way to cope with the trigger.
Hayes SC. Get Out of Your Mind and Into Your Life: The New Acceptance and Commitment Therapy, New Harbinger Publications; 2005.