Dear Manoj ji,
Let me give you yet another reason for marriage in Rahu-Mars that has not been discussed so far. This is a principle that I have not been trying much, but one of my teachers likes a lot. It is Iyer's principle of Sthoola and Sookshma lords of houses. The sthoola lord is the usual Rashi Lord. The Sookshma lord is the Lord of the Star where the cusp of the particular house falls. So in this method each house then has two lords.