So torn between two women

One does not want a relationship wants me to date other women and loves hearing all about it. It's great to be able to talk openly and honestly. The other knows I'm dating other women but doesn't want to talk about it and wants to turn things into a relationship. Part of me wants to be part of a happy couple, but I know it will eventually end. The way I feel with her now won't always be that way. But how long can I go on just dating with someone who may want something more?