There is no specific Islamic teaching in the Quran or Hadith that dictates which side of the bed the wife should sleep on. The arrangement is a matter of personal preference and mutual agreement between the husband and wife.
In other words, neither the Quran nor the authentic Sunnah prescribe any particular sleeping position for either spouse. While some cultures might have specific customs or traditions surrounding sleeping arrangements, these are not based on religious texts.
It's important to emphasize that Islam focuses on marital harmony, mutual respect, and consideration between spouses. This principle extends to decisions about sleeping arrangements, which should be made collaboratively based on comfort and convenience for both partners. The best arrangement is the one that promotes a healthy and loving relationship.
Therefore, focusing on arbitrary rules not found in Islamic scripture can distract from the core values of marriage, which emphasize love, respect, and shared decision-making.