Chemistry is often used to refer to the emotional or psychological feelings and interactions between two people, usually in a physical/romantic way. However, you can also use this to talk about the bonds or interactions between individuals in a general way. For example, if you say that you and your best friend have great chemistry, it means that you have a great emotional bond.
Ex: My boyfriend and I had great chemistry from the first day we met.
Ex: It's not going to work out with my blind date, we didn't have any chemistry.