I tend to agree with Gavriela.
Synasatry as such, simply tries to establish compatibility. However, people can be compatible in many relationships, parent/child, employer/employee, business partnerships, friendships, etc - and of course romantic.
What may work in a friendship may not work for a romance, and what may work for a romance may not work for a long term marriage.
Moreover, promise in natal charts is just that. Someone might well have indications of compatibility with someone else but that certainly doesn't mean that they will fall in love or even notice each other. There have to be other triggers to get a relationship going. Whether Astrology can recognise these in advance, I'm not sure.
Traditional Astrology did not use synastry in the modern sense, compatibility was judged on the basis of temperament. I'm not sure if Vedic Astrology uses techniques similar to Western synastry.
However, in the context of marriage synastry it should be remembered that in the cultures of the sub-continent marriages are often arranged, so the context is very different from the West. (Indeed much before the nineteenth Century marriages were often arranged (or at least encouraged by families) in Western Europe, certainly for the nobility and middle classes. So ,traditional Astrology also operated in a different context.
Synastry can be useful but be careful of taking a simplistic view. For long term compatibility the relationship needs to have stresses as well as facilitating factors - often the best and most productive relationships involve quite major tensions. Even with communications you need to be careful, indications of easy communication between two people may simply denote that they will quickly realise they don't like each other!
