I don't know about (and cannot talk about) kamma from any previous life.
I believe though that people's intentions and actions have consequences during this life, at least.
For example if one is greedy or angry then that causes suffering;
and if one can renounce greed and anger then that's conducive towards the ending of suffering.
I suspect that Hinduism (not to mention Buddhism) sees a link between Karma and caste. For example, this article Karma in Hinduism claims that:
Chandogya Upanishad 5.10.7 distinguishes between good birth such as birth in a spiritual family, i.e., (brahmin caste) ... Thus, the doctrine of karma comes to explain ... even differences between members of the same species, such as humans.
It has also been argued that Karma has a role in Hindu society as a whole. When one abides by their caste duty good Karma is earned and vice versa; and the Karma one collects is reflected in the next life as movement within the Caste system. The promise of upward mobility appealed to people, and was made plausible through Karma. This effectively "tamed" the lower castes into passive acceptance of the status quo. Thus, the Karma doctrine discouraged actual social mobility.
I don't think I have a supernatural ability to see past lives or to know how they affect this life.
Instead I see the four noble truths as being true for everyone, applicable to everyone, in this life.
Actually I recommend this short article: The Taste of Freedom. It suggests as an experiment, imagine a prisoner: is he free? Take him out of prison, give him a middle-class lifestyle: now is he free? Make him a great king: now is he free?
I think that the point of Buddhism is to acquire freedom (e.g. freedom from suffering i.e. cessation of dukkha, and also freedom meaning autonomy) somewhat regardless of our circumstances.
In this article, Bhikkhu Bodhi wrote, talking about the Dhamma's being "universal",
the Buddha placed no restrictions on the people to whom he taught the Dhamma. He held that what made a person noble was his personal character and conduct, not his family and caste status. Thus he opened the doors of liberation to people of all social classes. Brahmans, kings and princes, merchants, farmers, workers, even outcasts — all were welcome to hear the Dhamma without discrimination, and many from the lower classes attained the highest stage of enlightenment.
Within the wider Indian society the Buddha did not attempt to abolish the caste system, which, it seems, had not yet developed into the complex, oppressive system it became several centuries later. However, he flatly rejected the orthodox brahman view that a person's class status was an indication of his intrinsic worth. Within the Sangha, the monastic order, he completely disregarded all distinctions of social class, declaring,
Just as the waters of the four great rivers flow into the ocean and become known simply as the water of the ocean, so when people of all four social classes go forth as monks in my teaching, they give up their social status and become known simply as disciples of the Buddha.
I'm sorry that your marriage hasn't worked out in the way you hoped it would. Romantic relations are often like that, even notoriously like that.
I'm sorry too for the man you talked about, who was crying. I was told a story yesterday evening, of an Englishman:
An old labourer 85 years old remembers his hard life in Suffolk. "There was nothing in my childhood, only work and no games. One day a year I went to Felixstowe with the people from my church ... that was my pleasure. But I'd forgotten one thing: the singing, there was always singing then ... in the churches, in the fields, in the trenches during the war. So wasn't telling you the truth: I did have pleasure, I had singing."