Have you read the book "The Highly Sensitive Person" by Elaine Aron? You might fit that description as well.

I've read Jung's perspective on introversion and it helped with understanding things. Though I'm not as introvered as you and do enjoy a good live conversation, I can definitely relate.

As far as whether it's fair to your partner, I wouldn't worry about that. You are who you are and he's with you because he must like who you are. Being single means you can succumb to loneliness. Maybe it's a good the relationship is long-distance.

The only unwanted advice I can give is to challenge yourself once in a while and step out of your comfort zone when you feel it might be worth it (for example, a person like you will be at a gathering and you can hang out with them in the corner the whole time). If approached with the right attitude, it could end up being rewarding.

I grew up being shy and introverted and not even feeling comfortable around my own family members. Solitude was always heaven. But now I yearn for social connection due to a life lived indoors (these days).