How good relation is needed to invite a fame sim over?

My non-famous sim visited a 1 star famous sim. They talked a bit and got a slight green relation bar (10-15%). Then, back home, I wanted the non-famous sim to invite the 1 star sim over, but only can invite the clubs she is a member to to hang out... There's no way to invite only that sim.

So, is this because their relation is still poor? If so, how strong must their relation be before a 1 star sim can be invited over?