In Islam, the topic of physical affection, including kissing, between spouses is addressed with some differences of opinion among scholars from different schools of thought. Generally, the majority of Islamic scholars agree that affection and intimacy between a husband and wife are allowed and encouraged within the bounds of marriage.
Many scholars consider kissing one's spouse on the lips to be permissible as it falls within the boundaries of permissible intimate acts within marriage. It is seen as an expression of love and affection between a husband and wife.
However, it's important to note that cultural norms and personal interpretations can also influence people's views on this matter. Some conservative interpretations may suggest avoiding public displays of affection, while others are more lenient.
The key aspect emphasized in Islam is maintaining modesty and privacy in all intimate acts between spouses. The Quran and Hadith (sayings and actions of Prophet Muhammad) encourage the husband and wife to be loving and compassionate to each other and to fulfill each other's needs while respecting one another's boundaries.
As with many matters in Islam, individuals and couples should seek guidance from their local religious scholars or imams if they have specific questions or concerns about the permissibility of any particular action within the context of their marriage.