"He is my friend."
Translation:C'est mon ami.
A friend is a friend = un(e) ami(e) est un(e) ami(e), and you can keep it as such if you don't want to go into the details of your relations with that friend. In French at least, "un(e) ami(e)" does not have any romantic connotation.
So if you want to express that it is your boyfriend, you will use "petit(e) ami(e)".