Sandy really likes talking to belinda. every time she speaks with her, sandy feels calmer and less anxious. sandy is using her interactions with belinda to fulfill her

Sandy is using her interactions with Belinda to fulfill her "physical needs".

Needs are vital to human functioning. The idea of human needs comes from our biological nature, a nature that can be comprehensively seen in both mental and physical terms.  

Once the physical survival and security needs are being regularly fulfilled, an issue for adoration, friendship and having a place start with develop. This result from the way that individuals are amiable and require associations with others.