As others have said, a "boyfriend" implies the following:
a. a male person
b. a romantic relationship,
c. but not married ("husband") and not engaged ("fiancé").
By comparison, "partner" implies the following:
a. any gender
b. some type of relationship. Depending on the context, it could be a romantic relationship, a formal business arrangement such as co-owners of a business, a collaboration between two artists, or any other type of cooperative activity between two or more people.
In the present day "partner" without qualification typically implies a committed romantic relationship without specifying whether the commitment includes being engaged or being married.
If the person is not a romantic partner then we usually identify the type of relationship by saying something like "business partner", "law partner", "artistic partner", or using a different word such as "colleague".