Lagna (D1) and Navamsa chart (D9)
From a person s lagna chart, the 7th lord denotes spouse and marriage. Its significance or amsa can be found in Navamsa chart (D9).
This is read from the spouse s chart also.
The 1st house of one chart is the 7th of the other chart, for matching, which gives that many choices of marriage, as time unfolds. It is NOT necessarily be the one-to-one karmic connection. That way nature keeps its multiple choice of marriage-pairing intact for progeny and propagation of genes.
When the D9 of one chart matches the D9 of the other chart, then that is the karmic past life connection, of these two souls.
Then these two are destined to become couples and live their life together, in this janma, not necessarily of Love ( OMG :( ).
For Nakshatra matching
For Marriage Horoscope matching of boy and girl, use nakshatra matching.
For Horoscope matching
Consult an expert astrologer for Matrimony matching or marriage compatibility.