There was reason perhaps. After Kanha saved Rads from being dug, Radhika pleaded to the Lord to be sent back to her husband. Though her husband didn't trust her, he was her life. Kanha knew this. However, what was the guarantee that Radhika won't be treated again in the same manner. There can be again such incidences and Radhika would be suffering every moment.
Now that Dev's thoughts are being opened to the audience, we can see the reason as to why Kanha came down. He did not come down to merely punish the evils (it was a reason though) Rather he came to guide Dev in the correct path so that Radhika wouldn't have to face such situations repeatedly. Dev's trust was very weak. Although he loved Rads more than his life, he also took her for guarantee...he did not trust her, not because he didn't want to...but because he didn't have an option. He acted like an RP and not as a husband. Being burdened down by huge responsibilities of RPship, he took several wrong decisions (Dev himself said that he did many things as a RP that his conscious didn't allow him to do).
Being separated from Radhika for the whole 1 month, Dev realized her worth. It was needed to build that fear in Dev's mind...that his wrong decisions can distance him from his life (Rads). Following which Kanha came in disguised as Radhika...because Kanha wanted to ensure that his devotee doesn't get treated in the same manner again. Thus Kanha's repeated but subtle hints and advices to Dev which are finally showing effect. Back then, when Rads/Kanha would hint and point at his mistakes directly but gently, Dev would be left pondering. That's because Dev was realizing his mistakes, slowly but surely. Now Kanha's efforts are showing its colors. Dev trusts Radhika more than anyone else. Kanha's games with Barkha made Dev doubt her past accusations towards Radhika as hallucinations. Dev understands that he made grave mistakes and would never repeat them again. But there is more to come. Dev's conversation with Rads/Kanha yesterday revealed all this. He doesn't want to loose Radhika, his trust on her is stronger than ever before. I guess one of Kanha's work is accomplished. Because with Dev being in Radhika's side, she can face the toughest weather...and not even stumble :)