Well, we've been together for 25 years now, married for 21. We met through a mutual friend (he was dating her at the time - we're both still friends with him, and see him somewhat regularly socially). It's just worked, over these long years of struggle, in part because we balance each other.
Her social life revolves around a very short list of very close friends. The people she loves, she loves, and she's incredibly devoted to them. But she's also distrustful and fearful of others. She's prone to resentment, especially of the careless and irresponsible type of extrovert who gets away with being a flake because they're charming. Her way of dealing with her fear of other people is by being prickly, which makes it hard for people to get to make the effort to get to know her and get past her defenses. So poor social choices she makes due to introversion end up making the problem worse. But some people do make the effort, because she's incredibly intelligent, talented, and beautiful. The work is hard, but the reward is great.
So how we started... well, we met and started dating. Apparently, I was attractive enough to get her past her fears to really reach out. After our first date, she went home and broke up with the boy she didn't tell me about! Then she sought me out at work two days later - this was the pre-internet days when you actually had to go see people in person. On our second date, I was struggling that day with some private family difficulties, and found I could just open up to her about something I'd normally keep to myself. It was also a point in my life where I was getting tired of my ladykiller lifestyle (and I am good at that), and was ready to settle down. We fell in love very quickly, and were engaged in just a few months.
I bring a very different personality to our mix. I find just about everyone I meet interesting in some way or another. I'm very open about my life, except for a small zone of privacy that is very strict. If someone disappoints me, I just ignore them and move on to the next interesting person, rather than stewing in anger and hurt feelings. Because she lets so few people in, the stakes are higher for her. For me, with more friends than I can really manage, the stakes of any one person are lower. And it's not just people, it's life in general. Little setbacks don't get me down. I enjoy risk and unpredictability. She likes stability.
For 20 years, I worked in the enterprise corporate world, a very safe career path that keeps me easily employed and well-paid, because it makes her feel safe and happy. But it makes me feel stifled and frustrated. Now, it's time to swap. I'm leaving it all behind for my own startup (this is actually my last week of dayjobbing), and she's terrified, but going along with it for my sake.
Being able to give enough to let the other have what they need, if not always what they want - that's how to make the introvert/extrovert relationship work.
Interestingly, it works in other ways as well. She often brings me to social events to run interference for her. I can "hold court" (her term) anywhere I go, charming people and bringing them into my orbit. She can stay with me if she feels she needs cover, or wander off if she finds something to do or someone to be with, knowing that I won't be bored.
Does this help some?