Familiarity is good, but it’s the fruit of the process of fostering relationship. When we start the relationship process, it’s just the seed… not the fruit, and you end up becoming over-familiar too quickly. There’s some degree of formality that you have to keep in mind when cultivating relationship. This comes from knowing your boundaries.
When you know your boundaries, you can act with respect in relationship, and be generous while still maintaining the respect-zone that formality creates.