Current US stats are 14.04/100k, with men 3.9x more likely than women.

As the following example doesn't depend on the actual numbers, let's eyeball that and imprecisely say the married women's suicide rate was 5/100k before and 4/100k after: this is a 20% reduction, but I don't even need to look up marriage rates for it to be clear that nowhere near 20% of all marriages end in suicide.

In the other direction, suicide isn't and never was the only was out of abusive relationships. It's a desperate path for very extreme situations, and the divorce rate being much higher than 20% means there may be a correspondingly higher abuse rate.