That is not true at all

Your girlfriend is wrong the truth is by her allowing the father to be the custodial parent she would be paying him child support, if she were the custodial parent he would be paying her, child support is based on the income of both parents even if the mother did not have custody the fathers income is counted and if he made less than her then he would pay less child support to her but he would pay the mother. so the mother is either confused or does not want you to no she did not want to raise the children.

Mom might not be telling her boyfriend what she knows is the truth. The statement she gave the boyfriend is self-serving and she might have said what she said for the boyfriend's benefit.

Another possibility is that mom made a deal with dad tying the amount she paid to custody. It's wrong to do it that way. The court won't allow it if it's too far off. It does happen.

Any non-custodial, higher-earning parent can make it back to financial health faster. Maybe mom meant that she would realize more in her pocket if she didn't have custody. Children can get expensive. Having a spouse who is a lower earner can wipe out the family budget. If the ex was a spendthrift - getting away is the only way. Cutting the outgo can get very attractive.

Whatever the case, women have the right to do what men have done for years, not without consequences, but men were not in the same class. Men seemed to fair better both financially and it didn't draw the kind of opinion that a woman who did the same thing. In fact, few women didn't end up with custody.

These days, it's becoming a more equal matter. Men are more hands on and women want a life. Children get caught in the middle.

Soiunds like you are looking for a free ride, why would the fathers $$$$ have anything to do with your thoughts, its about the kids. Do you have a job ?

It doesn't sound like these payments are from child support. This sounds like an alimony situation, where one partner has been mandated by the court to help pay expenses to another. Unfortunately, most alimony situations are unfair and punitive. There isn't a lot you can do to get out of them either.

In any case, the non-custodial parents should still be liable for child support. However, the alimony payments may offset any benefit received from money for children. These payments can bleed you after awhile, and they can only be re-evaluated if the ex agrees, or if there is a significant change in their financial situation.

Have your girlfriend speak with a lawyer if it continues to be a persistent problem. Also look to see if there are any true imbalances in child support. If this is the case, rather than alimony, then it may be possible to correct the problem, and ensure money she cannot afford to lose stops going out the door.