Name : Sumit Nag
Date of Birth : 18-05-1982
Time of Birth : 18:00 Hrs (IST)
Place of Birth : Delhi (India)
Query :  When exactly my marriage will take place and will it be a love or an arranged marriage?

Sumit,
Regarding your exactly when your marriage will take place, I will like to have exact time of birth, and will have to tested with divisional charts. Anyways according to Vedic astrology my observations are as follows:
1. Libra ascendant and lord Venus is placed in its exalted sign but in sixth house with Moon. Venus also represent house of miseries. Jupiter retrograde is placed in the house of ascendant giving strength to the house of spouse. Mars is also giving strength to its own house of spouse.
2. Spouse house lord Mars is conjunct with Saturn lord of trine, indicating some relationship, but combination of Mars and Saturn is afflicted by eighth house and blessed by ascendant lord Venus. Indicates that due to some emotional reason and in separation situation too.
3. I feel marriage with the blessings of elders.
4. Mahadasha lord Mercury is placed in eighth house with Sun, indicates that possibility of delay is further confirmed. Next phase is of Mercury Rahu or Mercury Jupiter can give marriage. Rahu is placed in the house of fortune can give marriage at any time, where as Jupiter is placed in ascendant and placed giving aspect to house of spouse.
Period will start from Middle of August 2013. I am not saying denial of marriage.
I have not tested Navmansha chart.