What’s life like in San Diego?
Former Bostonian here. For you, it might not be much of a culture shock, but for your partner it might be. The lifestyle here is slow and laid back. It does take time to adjust to it. When I first got here I found it annoying that the person ahead of me was chatting with the grocery checker - hurry up! But after a few months, I was the one chatting. A fair number of people, though, never get used to the slow pace and have to move back East.
The weather is lovely. You never realize how much work it is to put on coat, boots, scarf, hat, earmuffs, and bring your umbrella. Here, you just get dressed and go out. For me, the moment came when I was taking out my trash cans, at night, in December, in a t-shirt, and I wasn't cold. If it's in the 50s or 60s, you'll get to laugh at the natives in puffy coats and earmuffs.
The weather can have a downside, though. Seasons barely exist. There is no snow at Christmas. In the fall, there is hardly any color. Flowers bloom all year, and there isn't a profusion of color in the spring - our flowers burst after we get the rare hard rain. You will not recognize most of the trees and plants, and have to learn like a little kid.
As others have said, public transit here is pretty poor. Yes, you can get from place-to-place on transit, but it isn't cheap and it can take you 3X longer than driving. A car really is a requirement here. Some people do make it work without a car, but it's not easy.
Even coming from high Boston rents, the rents here will be a sticker-shock. Bring your checkbook when you look at apartments, because the available ones go really fast. If you don't put money down right away, you'll lose it. And although our traffic isn't L.A. (or Mass Pike) bad, living near where you work is a benefit - especially when you first get here.