This isn't the first time I've read Dracula and, of course, I've seen Dracula movies, although not recently; but this time I'm really noticing the love story between Jonathan and Mina. Their relationship is so mutually loving and respectful and caring toward each other, that I wonder why I didn't notice it in past readings.
The first thing that struck me was their special shorthand that they use to communicate to keep their letters private. They must have spent a lot of time together to devise and practice their personal shorthand and, obviously, enjoyed doing it.
Then, when Mina finally learned of Jonathan's whereabouts after his long imprisonment at Castle Dracula, she traveled alone to an unfamiliar place to be with him and help him recover from his trauma. He trusted her with his diary and left it to her judgement, which he respected, to decide when and if she would read it. Even though he was ill and might lose his ability to provide for her, she married him on his sick bed without hesitation, out of pure love.
Once they knew that Dracula had been feeding on Mina and planning to make her a vampire, Jonathan resolved that she would not become a vampire alone. He also vowed to do whatever he could to destroy Dracula and save Mina's life.
Their relationship is not one of practical pairing or convenience like many marriages during that time, but one of deep mutual love and respect. They weren't just husband and wife, but best friends and soul mates.