Food play aka Sitophilia meaning eating food off a partner's body, what is the psychology behind it ? I mean, if someone ate bbq chicken from my body,

I believe food sex developed in the days when discussing sex was forbidden or censored or not socially acceptable. People would use other things (like food) as proxy symbolism to discuss sexual interests or fetishes. Also, certain foods stimulate sensory pleasure, like a partner having lime juice or spices on their lips before engaging in oral sex.