Jeri Ryan is sad Seven didn’t fall for the Doctor
The Doctor and Seven of Nine had a lot in common on Star Trek: Voyager. They both felt out of place. The Doctor wanted more of a chance at humanity while Seven began the process of rediscovering hers. The Doctor had never known love or any other human emotion, and Seven’s had been suppressed to the point where she had to learn them all over again. And when the two began a friendship, there was more than a little bit of magic.
In the fifth season episode, “Someone to Watch Over Me,” the Doctor teaches Seven how to date, and it doesn’t take long for him to realize he has feelings for her. Just when he’s about to tell her how he feels, she squashes his hopes by telling him she doesn’t believe there is a suitable mate on board Voyager for her. Then the Doctor tells Seven the last few days have been “unforgettable.” As she walks away, there’s sadness in his eyes as he’s just learning what it means to be in love.
Jeri Ryan wanted a relationship to happen
Jeri Ryan, who portrayed the ex-Borg drone, Seven of Nine, actually wanted a relationship between her character and Robert PIcardo’s as she loved the dynamic between the two of them. She said that they shared the same “being outside humanity and looking in aspect.” [The Fifty-Year Mission The Next 25 Years by Mark A. Altman and Edward Gross p. 612]
"I loved the relationship that Seven developed with the Doctor, and I’m still sad Seven didn’t fall for him. He was so sweet."
A relationship between the Doctor and Seven would have certainly made more sense than the quickly fabricated one between her and Chakotay. After all, Seven and the Doctor had developed a rapport, had become friends, and were both trying to find out where they fit in the world.
Having a romance develop between the couple would have added more humor as they both struggled to understand what it meant to be in a relationship. And, on top of that, the pair would have been able to grow in humanity together and realize they wouldn’t be alone again. It wouldn’t have been a perfect pairing, but it would have been wonderful to see the relationship unfold. And a few more duets would’ve been a bonus!