The conversation stopped mid-sentence. Nothing happened, nothing was said, and the explanation you have constructed since then has been revised about forty times. The worst part is not the ending. It is that there is nothing to examine.
Before going further, one honest limit: you almost certainly do not have their birth details, and without an accurate time and place there is no chart to read. Anyone offering to explain their behaviour from their sun sign is guessing. What is actually readable is your own chart — and specifically, the pattern of what keeps arriving in it.
The 7th house describes what you attract
The 7th house governs partnership. Its sign, its lord, and any planets sitting in it describe the recurring character of the people who enter your life in that role — not one person, but the type that keeps appearing.
This is the part people find uncomfortable and useful in roughly equal measure. If emotionally unavailable partners are a pattern rather than an incident, the pattern is in your chart, and it is describing something about what you are drawn toward rather than something about your luck.
The placements that produce distance
Ketu
Ketu in the 7th house, or influencing its lord, is the closest thing Vedic astrology has to a signature for abrupt, unexplained endings. Ketu signifies detachment and severance — not conflict, but the sudden absence of attachment where attachment was. Relationships under strong Ketu influence often end without a rupture. They simply stop having a reason to continue, and one person feels that before the other does.
Saturn
Saturn in the 7th produces distance of a different kind — caution, delay, and emotional withholding, often from a person who is genuinely committed underneath it. Saturn does not leave. It just never quite arrives either, which can be harder to read than leaving.
An afflicted Moon
The Moon governs manas — the mind and emotional capacity. A Moon under pressure from Saturn or Ketu describes someone whose ability to stay present in closeness is genuinely limited, not withheld out of malice. This applies to both sides of the equation, including yours.
What this does not mean
It does not mean you are cursed, and it does not mean the pattern is permanent. A 7th house with difficult influences describes a default setting, not a sentence. Defaults can be worked against once they are visible, which is most of the point of looking.
It also does not excuse the behaviour. Astrology explains mechanism, not morality. A chart that predisposes someone toward avoidance does not make disappearing on another person acceptable, and any reading that leaves you more understanding of them and less clear about yourself has gone wrong somewhere.
The more useful question
Not why did they leave — that answer is unavailable and would not help much if it arrived. The better question is why this keeps happening, and that one is answerable from your own chart.
The Vimshottari dasha matters here too. Relationships formed during certain periods — Rahu in particular — tend to carry an intensity that does not survive the period ending. People often describe those as the ones that made no sense afterwards. They made sense at the time because the timing supported them, and the timing changed.
Knowing which periods of your life are structurally unsuited to forming lasting attachments is genuinely useful information. It is also considerably more actionable than a post-mortem on someone who is not answering.