Since coining the phrase “poly-dating,” I have been asked the following question: isn’t that cheating? No. No, it is not. Until you are in a committed, monogamous relationship (whether you had ‘The Talk’ or you just know you both want to be pursue a future together), you do not need to explain yourself to anyone. You can date anyone you want. But, as soon as things start getting serious with one person, then you must break it off with the others. If you’re planning on having sex with one of your prospects then you need to break things off with the others beforehand, out of respect for all parties involved.
Once your new relationship is secure you can mention that there were others you were dating until they made you realize that no one else could measure up (may as well spread it on thick if you’re going to go there), but don’t volunteer the information if no one asks because it really doesn’t matter what you did before things got serious.
And, in general, there is no reason to continue having a friendship with any of the rejected prospects. You were dating to see if there was a future together; there wasn’t, and that relationship is now over. Your new significant other will not appreciate you having a friendship with someone you were dating at the same time.