How about a nice medium...
A girl that is fun, but not monogamistically challenged?
You're either bored and in a relationship, or you're single and lonely.
There's rarely any electricity left in a relationship after a short period of time. Feels like you either have to accept the fact that you're going to be bored and in a relationship or you're going to be single and lonely.
Unless the two of you have EQUALLY busy schedules and see each other enough to stretch that "short period" of time into a period of time that may or may not be relatively longer than that "short period" in reference to Shakespeare's "conserve love."