1) the property is standing in joint names of yours and that of foreigner .
2) if at time of purchase foreigner was represented by advocate he ought to have POA in his favour for registration purposes .
3) in any case dont challenge the said registration of sale deed .
4) if you do so it will open a pandora box and purchase of land may be called in question .
5) merely because foreigner is gay has no bearing on his ownership of land
6) better sell the land and split sale proceeds