Details: They were highschool sweethearts and believed they would grow old together and he fathered her first child, Lucas Scott, but Dan then abandoned Karen and their son to go off to college. He then met Deb and had a child with her. In Season 4, they grew really close again after Keith's death and dated for a while, until she found out he had killed Keith.
Details: After going on a Ravens away game together they realized they were able to get on well and they later went on to date although due to Karen's complicated relationship with Keith it never progressed to anything more.
Details: Karen was a student for Andy's at college and despite the age gap they started dating and started a serious relationship. But when Andy was deported Karen realized her feelings for Keith and ended their relationship as well as Andy wanted children whereas Karen didn't. After Keith's death the two recoiled and together raised Karen and Keith's daughter Lily.
Details: He was her friend for fifteen years. She kissed him before traveling to Florence, Italy. She then found out that Keith had been drinking when driving Lucas to pick Karen up from the airport. When she had finally forgiven him, he asked her to marry him. She said no. After the attempted murder of Dan, Karen finally realized that she loved Keith and they kissed. Keith was then arrested for his attempted murder. Later, Karen asked Keith to marry her with his response telling her that he was going to ask her. Soon after, Dan murdered Keith out of what he thought was getting revenge. Little known then, Keith died leaving Karen pregnant with her second child, a daughter, named Lily.