A couple points need to clarified here.
1. Do you have children as well to support?
2. Where you are living, how do the courts see the contribution from the new partner? For example, does just living with the non custodial parent make a differnce in the amounts require for child support? Is it only the married partner's wealth that can affect the non custodial parent's payments?
Also be honest --and generous with yourself. Do you want children and are you worried that this arrangement makes it difficult for you to have your own children.