The Soulful Atom

We are celebrating Gauri-Ganapati in Maharashtra at this point of time. And while I was visiting my granny to invite her for the haldi-kumkum (wiki: Haldi Kumkum, or the Haldi Kumkum ceremony, is a social gathering in India in which married women exchange haldi (turmeric) and kumkum (vermilion powder), as a symbol of their married status and wishing for their husbands' long lives) which takes place at every house where gauri-puja is performed, I had a revelation, which is also a question to all these generations celebrating this festival and the rest.

Lets start with what is gauri puja?
A google search says: "Gauri Puja - worship of Gauri - begins on the 11th day of the bright half of the Hindu month of Ashadha (June-July). It is believed that Goddess Parvati got Lord Shiva as her husband after performing the ritual of this worship and they lived happily ever after.
In fact it is the combination of two festivals. Gouri-Ganesha Chathurthi. Mainly the ceremony of birth of Ganesha. The previous day will be celebrated as the Gouri pooja. She is the mother of Ganesha.
The bride worships the Goddess Gauri by performing Gauri Pooja. The Goddess Gauri is highly revered as it is believed that she is a manifestation of Shakti, the mother of the universe and the power and energy by which God creates, preserves and destroys the world. She symbolises motherhood, fertility and the victory of good over evil. "

After this pooja is performed, all the married women visit each other and exchange haldi-kumkum. So while discussing about the puja, we also talked about inviting an aunt who is a widow. Since the ceremony is only for married women whose husbands are still alive, in earlier times, including all the other atrocities against widows, they were not invited even to celebrate such festivals. But now since times have changed they too are happily welcomed to be a part of festivities.

Now my question is people since olden times believed that the soul is immortal. So even when a man dies his soul should be alive, is alive. The marriage is said to be for seven births or even more, for ever. So it means that once married, how does the birth or death of the body matter? Aren't the souls married? And if so why would any woman be a widow or a man a widower?
So why are the widows treated so, if their husbands are still alive and exist in the universe? And if not then why believe in the holy union of marriage? Why get married if we do not believe in what it has to say? Why do birth and death make us do away with our beliefs then?

I may be ignorant about the other facts of these things. My doubts may even be childish musings. But why does the society and religions contradict their own beliefs?

There is much more to this question and many doubts are still being formed, but I had to put this forth. All views are welcome.. Please put forth your perspectives!