Reporters and sources who share an interest in a story find that they share an interest in each other. He could have his career or his love, but not both. But times have changed, the rules have changed. If the newsroom was cleared of everyone dating, married to, or living with a potential source, it would be close to empty.
Journalists depend on the public's trust to do their work.
Their personal choices, and those of their partners, have an impact on their professional lives and the credibility of their news organization. Even if only those reporters with the highest integrity were hired, those who could never be swayed, the audience would suspect that the reporters are as human as they are. The company has the dilemma of treating their highly-principled employees with respect and keeping the trust of an audience that suspects the worst. Today, stories on even the most isolated beats, such as religion or sports, are entwined with business and politics. And, if it's not the life's partner writing the story, it's likely to be the tennis partner.