you are using "temple_to" ... try using "temple_of"

vanilla Roma;
Code:
building temple_of_love
{
    levels temple_of_love_shrine temple_of_love_temple temple_of_love_large_temple temple_of_love_awesome_temple temple_of_love_pantheon 
    {
        temple_of_love_shrine requires factions { scythia, pontus, greek_cities, }

G