If you have a new female partner that wants you to be the cuckold, then this can be an odd feeling. If you do not feel comfortable being the cuckold but you really like her, then you will need to really think about what is more important to you. A lot of the time, when you really like a person you will end up doing things that you never thought you were capable of liking or being comfortable with.
Talk to Her
It is a good idea to talk to her about it and really see what about this idea turns her on. It may help to see her side of things and she may be able to let you know what it is about it that turns her on. The same things that turn her on may help to do the same for you when it comes down to it.
Start a Trial
If you feel like this is something that you can do, then it is wise to start it off on a trial basis. Just remember that it will probably be pretty difficult to go back to how things were once you have already begun. If at any point you begin to feel uncomfortable, then you need to tell her. The sooner you have her stop the easier it will be on your relationship should you try to go back to where you were before. However, a trial can be a great way for you to see that you really do actually enjoy being the cuckold.