Most normal people are fairly well-balanced adults, parents, citizens... Kuja Dosha's Martial characteristics rarely reach the criminal extreme of physically annihilating the partner.
Normal human moral development provides checks & balances within the ego which allow Mangala's natural vitality to flow in safe & creative but vigorous ways.
For example, neechha Kuja (Karkata) is passive- aggressive & prone to emotional volatility.
Yet, when this same miserable Karka-Mangala occupies the janma lagna, Kuja becomes a "yoga karaka" or a graha of highly auspicious significations. As yoga-karaka for Karkata lagna, Mars becomes the ruler of lucky domain-5 and dignified domain-10.
So, the 25%-strength of Kuja dosha which is generated when Kuja rises in Karka, is compensated by native's strong character & good fortune. The native may not have a perfect marriage, but their spouse shares in the benefit of the native's public dignity and auspicious children.
The biggest single improvement in Kuja dosha comes from the aspect of a benefic onto Mangala himself or onto yuvati bhava.
Aspects from Vrihaspati are very curative, giving the person a fundamental generosity & goodwill toward all.
Beneficiaries of a Guru drishti include the beleaguered spouse

because Guru's drishti upon Kuja improves the viewpoint and expands the sense of humor. Marital Anger is still present but it feels much softer and becomes bearable through laughter & overall goodwill.
Aspects from Shukra or L-9 upon the marriage house are also softening & pleasing & will also improve the experience of living through marriage with Kuja-dosha..
Even the aspect of Shani on either Mangala or the 7th house will give longevity to the marriage. Although the partners will be oppressed, they will be loyal to their vows & the marriage painfully long-lived.