At the very least when you are married to your children's father or mother, you are in a position of commitment and respect for your spouse that centers around compromise. (well that is how it is supposed to be anyway) Parenting is very difficult to do with someone whom you may be struggling to respect or trust with your child's future. Each person has different opinions and convictions on what is right, healthy, "normal" and what is not. This can make for some pretty heated debates about the passion both people feel for their side of spectrum.
I have heard many stories of hurting men and women who are struggling to do what is right for their children with little or no help from the child's other parent. This is very difficult but almost a blessing in comparison to the other side of the coin. The worst stories I have to say however, are in those where one parent is road blocking every effort from the other parent to set a stable and healthy foundation.
How are you expected to support the child's parent being a part of their life when they are standing against every grain of your efforts to raise a healthy child? How do you handle these situations when your kids think of you as the "bad guy" for taking a stand for righteousness and discipline? You aren't the "fun" parent to them and that hurts you. Feeling at a loss for answers? Sure, we all do at different times.
Bottom line is that you are only going to answer on judgement day of how you handled yourself when these situations arose. You will have to answer to how you have trained up your children regardless of how the other parent is influencing their lives in an unhealthy way and standing against you. Being that this is the case, we have to do everything in our power to show God through our actions at all times.