  We construct and explore the solution space of two non-spinning, mini-boson
stars in equilibrium, in fully non-linear General Relativity (GR), minimally
coupled to a free, massive, complex scalar field. The equilibrium is due to the
balance between the (long range) gravitational attraction and the (short-range)
scalar mediated repulsion, the latter enabled by a $\pi$ relative phase.
Gravity is \textit{mandatory}; it is shown no similar solutions exist in flat
spacetime, replacing gravity by non-linear scalar interactions. We study the
variation of the proper distance between the stars with their mass (or
oscillation frequency), showing it can be qualitatively captured by a simple
analytic model that features the two competing interactions. Finally, we
discuss some physical properties of the solutions, including their
gravitational lensing.
