Grahmaitri is part of Ashtkoot Guna milan which is different from what I suggest that is Grah Milan. They both are different. In Gun Milan you have 8 different koots which are Varna, Vashya, Tara, Yoni, Grahamaitri, Gana, Bhakoot , Nadi. These are the 8 different koot of the ashtkoot guna milan. Grah Maitri is totally different and in this you match all the planets between both the horoscope and also read the 7th house which is the prime house of marriage and karka which are Jupiter in girls chart and Venus in boys chart as they are the determinant for happy married life.