The physical contact rules in a prison visiting room apply equally to all approved visitors regardless of their relationship to the inmate. The standard policy at most correctional facilities permits one brief hug and kiss at the start of the visit and one at the end. That rule does not distinguish between a spouse, a family member, a friend, or any other approved visitor on the list.
Correctional facilities are not in the business of policing the personal relationships or moral choices of inmates and their visitors. The visiting room exists to maintain human connection between incarcerated people and the people in their lives, and the facility's concern is security and order rather than the nature of the relationships involved.
What happens between consenting adults within the boundaries of those rules is not something corrections staff intervene in absent a specific policy violation. An inmate choosing to hug and kiss a visitor who is not their spouse is a personal matter between the people involved, not a disciplinary issue for the facility.
If you are present in the visiting room and find the conduct of other inmates and visitors objectionable, the options available to you are exactly what they would be in any public setting. Look away, focus on your own visit, or choose not to return to that environment. The visiting room is a shared space and what other people do within the rules is not subject to your approval or anyone else's.
The facility sets the rules. Within those rules, personal choices belong to the individuals making them.