since you are talking about a good friend, would you not rather say jsi instead of jste.
In this case I imagine a man visiting therapist and talking about his relationship. The therapist asks: Are you a good partner, Matěj?
Most often yes, but this sentence is not impossible. Sounds old-fashioned, but not impossible.
'First names + vy' are sometimes used as 'semi-formal style.' For example, your boss may address you like this.
Přítel meaning both friend and boyfriend is quite.. confusing. How to get the right meaning?
Přítel means a good friend. So when used by women it's usualy meant as partner. An ordinar friend is called známý or kamarád. But známý is not suitable for this leseon for its unusal grammar.
známý is rather just an acquaintance, not a friend.