There are a lot of nuances here, than just trust before marriage.
Many of the marriages are arranged ones, where the families arrange and negotiate the marriage. If the woman is not satisfied with any aspect of the marriage, some of them resort to these tactics to get rid of the husband.
Of course, there are those who actually suffer and are rescued by this law, but those are few and far between.
1. Free money. 2. Free sympathy from the society. 3. Feeling of revenge.
Remember that marriages for divorced women are extremely difficult in India. If the woman was separated from the husband, "as a victim", they have a better chance, especially if she is young.
However, due to severe misuse of the law, now the situation is such that any woman even as much linked to a court case regarding marriage issues, is effectively shunned from marriage.
And this affects genuine victims a lot.
People often marry under family and peer pressure. In such cases, trust becomes secondary. And many people realize it late that marriage is first and foremost a legal contract. Everything else comes after that.
I could sympathize until here. If you can't trust your partner why marry them in the first place? I find it hard to believe there weren't signs of things going wrong before she slapped a case on you.