While both of the Winchester brothers were popular with women, Dean was especially irresistible. Be it angel, Amazon, or even goddess, Dean intrigued them. Although Dean had to grow up at a younger age than most, he still retained a child-like energy and charm. He was intuitive, smart, brave, and inventive in moments of danger. Added to this, his fierce loyalty to friends and family and his big heart, make it easy to see why many fell for him.
All along, Dean wanted a life of stability. Unlike Sam, he didn't hide his hunter life from most of his romantic interests, showing that he wanted his partner to see all aspects of him. Lisa seemed to be his silver-lining after a life of tragedy and sacrifice. She was the romantic relationship that he had the longest. What makes Dean and Lisa perfect, and which other characters could he be with instead?
Dean and Lisa: She Knows His Past And Accepts Him
Lisa knows his history; she knows that he's a hunter and that he saves people. When Dean shows up on her doorstep in Season 6, he's broken, just having watched Sam sacrifice himself to be the vessel that holds Lucifer in the cage. She takes Dean, all of him, even his broken pieces.
When Sam comes back and Dean contemplates hunting again, she tells him to go, but that they can still stay together. Dean doesn't need to hide his hunter-side from her.
Other Character: Cassie
After knowing Cassie for just a short time, Dean had fallen in love with her and told her about his life as a hunter. He also seemed willing to try to make their relationship work. He cared about her so much that after one phone call, he dropped everything to come to her town to help out.
Sam was surprised at the depth of Dean's feelings, having known Dean to mainly have one-night stands. Ultimately, Cassie felt that his hunter lifestyle wouldn't mesh, but Dean was willing to give it a try.
Dean and Lisa: They're a Family
Dean and Lisa mesh very well together. Ben, Lisa's son, easily becomes like a son to Dean as well. Dean even teaches Ben how to work on cars. They develop a routine and rhythm together. When Sam comes back and circumstances make Dean bring Lisa and Ben to Bobby's for safety, Dean laments putting them in danger.
Lisa stops him. She says that the year that she had with him was the, "best year of my life." Part of that reason is that the three of them were a loving family together.
Other Character: Robin
Robin was his first love and kiss. For two months, he was at a boys' home, a place that ended up being a second chance and a sanctuary for him. During this time, he fell for Robin. Both were grappling with a similar issue. Their fathers expected them to follow in the family business, and they felt trapped. They both wanted to please their fathers, but they also wished that they could do something other than the family business.
Like Sam's teenage romance with Amy Pond where the two bonded over being freaks, Robin and Dean bonded on being the ones responsible for continuing their family's values. Their paths were set out for them, and eventually both came to terms with those paths--even loving them.
Dean and Lisa: They Have Obvious Chemistry
Dean knows that he's going to be dragged to hell, so he tries to experience a lot in that one year. One of those things is going to see Lisa again. While the two haven't seen each other for eight or nine years, they both remember their passionate time together fondly. Dean has been with many women, but when he's at death's door, it's Lisa whom he wants to see.
This chemistry and passion continue throughout their relationship together.
Other Character: Bela
When the two were together, Dean couldn't exactly trust her. Bela often double-crossed the Winchester brothers. She had little loyalty to them or their lives. However, whenever Dean and Bela were together, there was chemistry. They worked well together, and Bela would call Dean (not Sam) when she needed to get in contact.
No doubt, had Bela been around longer, these two would have become more than a potential romance.
Dean and Lisa: Can Communicate With Each Other
Dean and Lisa have an adult relationship. Dean is not a great communicator. He definitely hides a lot from Sam. With Lisa, he's able to have difficult conversations. When he's being pulled into hunting, she tells him that he needs to go, that it's a part of him. They try to maintain their relationship. Dean frequently calls her.
However, when things get bad, Lisa is also honest with Dean. She loves him, but she also knows that she and Ben can't be there with him in this.
Other Characters: Castiel and Amara
While these two otherworldly characters aren't exactly in a romantic relationship with Dean, it's no doubt that Dean has a connection to both. Castiel and Dean are such a great bromance that fans constantly ship them. In some ways, these two would be a great duo. In other ways, it's understandable why it hasn't happened. Apart from Dean not seeing Castiel in that romantic lens, Dean is pretty mean and judgmental to Castiel. Unless Dean were to shift his way of being, a potential romance between Castiel and Dean would be toxic.
Speaking of toxic, Amara (the Darkness) felt drawn to Dean. Amara actually consumes souls and seeks to destroy everything that her brother (Chuck/God) created. Later, Amara redeems herself and seems to adjust to Earth. However, a meaningful relationship between Amara and Dean could be interesting, but it's also toxic and imbalanced. After all, Amara is a goddess, and Dean is merely human.
Dean and Lisa: They Love Each Other
When Dean and Lisa were together, they were committed to each other. Although other women were interested in Dean, he didn't care. He didn't want anyone but Lisa.
After they were no longer together, Dean still dreamed of Lisa. These two loved each other. If Lisa ever recovered her memories of Dean, they could have a chance to be together again. It would be the ending that Dean deserves after his life of tragedy and sacrifice.
Other Character: Jo
Out of all the characters on this list, the one who best understands Dean is Jo. On top of also being a hunter, Jo was a child of a hunter just like Dean. When Dean blames himself for Jo's death, she assures him that she doesn't consider him at fault. Before she leaves, she touches his cheek tenderly.
There was a natural chemistry, love, and respect between them. They seemed to get each other. No doubt, had Jo lived, these two would have become an epic love, similar to John and Mary Winchester.