What you're wanting is not ethically wrong, though it might not be ideal for many people. My suggestion is to be VERY honest with women that you meet about what you want and let them decide for themselves. I don't think it's impossible for you to find a partner who will be happy with this arrangement, but it is important to remember that everyone's relationship needs are personal, and can change over time. Loving any other person is always a risk and we cannot control all the factors involved.
Ask for what you want, as honestly as you can, and be open to people regardless of their flaws and variances.