Don't know where you are reading these things, but please do forget them.
The 7th house and its ruler and any planets there will describe your relationship with others, whether partnerships or marriage.
In your case, mercury is the 7th house ruler. Mercury in libra looks for a partner, libra is the sign of marriage. On north node it indicates where your life path lies, forming partnerships is an important theme for you.
Located in the 10th house, these ties will tend to be with socially prominent persons, or those for whom their career is important.
Mercury is square Neptune, ruler of 3rd, so there could be difficulties in communications, or with your brothers or sisters.
Mercury also squares Uranus, so the contacts will come on fast and unexpected, and end just as abruptly.
You might find yourself being drawn to pisces, aquarians, gemini or virgo, or those with these qualities important in their charts (ascendent, moon).
Also, a double sign on the descendent tends to indicate more than one partner or marriage.