I wish to write something on "Mangal Dosh". Not going in details and things may remain unsaid but even then important insight and pointers are likely to provide over all perspective.
[Most imp note for all: Read the complete thread and not just part]
1/ https://twitter.com/ijyotish/status/1301044775722729474?s=20

Mangal/Kuja, the Senapati is an Agni tatva Graha who is hot-blooded & aggressive by nature!
THIS is the key!
Mars afflicting 7th Bhav results into quarrels, discord, physical separation in married life. if He simultaneously afflicts Shukra, the severity increases.
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Severe affliction, supported by other evils may curtail span of married life by divorce or death of spouse.
However, few crucial pointers must be taken into account:
1) Mangal is NOT the only Graha that can create troubles in married life. There are several other evil config.
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2) The biggest protection from Mangal's affliction of 7th Bhav and/or Venus, is Guru Maharaj. Guru, if himself not badly afflicted & weak, establishes YDP relation (repeated in D9 is even better) with Mangal hugely reduces the power of menacing Mangal on the 7th Bhav.
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For instance - Mars is functional malefic for Mithun/Kanya Lagna and also enemy of LL Mercury.
Mars afflicting 7th Bhav can create serious troubles in married life. However, if Guru is making UDP (Yuti/Drashti/Parivartan) connect with such a Mars decisively reduces the evil.
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3) Maturing age of Mangal is 28 yrs. We can corelate this in our lives. "Jawani ka josh" is @ peak in the prime youth. As yrs passes, person becomes mature/mallows down. Similarly Mangal's menacing ferocity w.r.t 7th Bhav, marriage and venus calms down gradually after 28.
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4) A strong and Yogakarak Mangal rarely damages a Bhav. For e.g. Exalted Mangal in 7th Bhav in Makara won't prove dangerous for marriage. OTC, it gives good spouse and married life.
(Note - Topic is Mangal Dosh so just pointing it solo. The whole chart must always be seen).
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5) Generally in my observation, Mars afflicting 7th, but not the Venus, does not create serious discord in Husband and wife. To have serious differences, Venus needs to be afflicted by Mars along with 7th.
As i said earlier, repeating again, Guru controls all evil of Mars!
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6) Mutual Mars-Venus matching (Husband's Mars with Wife's Venus and vice versa) creates great physical attraction in a couple. Good thing in today's world to save marriage.
Ending this -I hv so called Mangal Dosh in my chart. My wife doesn't have it.
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