I completely understand what you are talking about, I also need breaks between social interactions.
Lets call our introverted girl, Emma. she had two close friends, Kathy and Sharon. Both Kathy and Sharon were very extroverted and the three friends spent many happy times together, but it was much more draining on Emma to socialize for long periods of time than for either Kathy or Sharon. Emma felt she needed breaks between social interactions.
She felt very self conscious about this and wasn't sure how to tell her friends about needed breaks, so instead of explaining anything to her friends she would isolated herself for periods of time, where she would not answer the phone or door until she felt capable of handling the socially interactive again.
After one of these isolation periods, Kathy and Sharon confronted Emma. They were kind and concerned about Emma. When they were not able to reach her, they when through a great deal of worry wondering if Emma was okay.
The three worked out a solution to the problem, with Emma saying she would always answer the phone or door when they tried to contact her, and let them know she was taking a break. Her friends agreeing that she didn't need to talk longer, just let them know they did not have to worry about her. She had not considered how her isolation affected the people who cared about her.
Sharon was comfortable with this solution, but Kathy wanted to know why Emma would feel as though she had to take breaks. Kathy thought that as friends, Emma should not have to take breaks from her. It was okay if she needed breaks from other people, but why would she need breaks from Kathy
Emma tried to explain what it felt like to her as an introvert, how exhausting and mentally draining it could be for her to socially interact with any one for long periods of time, even with close friends. This explanation did not satisfy Kathy. Emma tried again and again to explain how she felt in as many ways as she could think of, but Kathy still did not understand. No matter how it was explained Kathy never did get to the point that she understood. Eventually Emma stopped trying to explain to Kathy, realizing that no matter how she explained, for some reason Kathy could not accept the explanation. Eventually Kathy and Emma spent less and less time together because neither could understand the other. Kathy concerning the breaks, and Emma because she couldn't give an acceptable explanation to Kathy,
With some of the pressure off Emma from Sharon, Emma had time to consider different aspects of the problem. She realized the largest part of the problem was how she herself viewed introversion. She had always viewed it as an emotional problem, one that had to be explained, one that was abnormal and unacceptable. She now saw the "problem" differently. Society may look at extroversion as more positive than introversion, but was that actually true. There were positives and negatives about both. Emma knew some people that were just naturally extroverted and some that were just naturally introverted, one was not better than the other. She did not judge these people because of this, so why did she judge herself? it was just two different ways of individual personalities.
Emma no longer felt she had to explain her introversion and wanting breaks, or her emotional needs to everyone. She eventually became comfortable just telling people who asked that she had a limited about of time for social interaction, that she needed a lot of alone time. From then on when she was in social situations and wanted to leave she just commented that she had reached her limit and was ready to go home.
During work hours when Emma felt she should be socially interactive with co-workers, she became to view it as part of her work duties, at times maybe not a pleasant one but one that was expected of her. If she became too stressed, she would excuse herself to go to the restroom and take a small break. When she was done, if her co-workers were still socializing, she would either feel she could continue the interactions or say she needed to get back to work.