I'll try to put it this way.
You're texting several girls right now. What's your level of commitment to them? Have you sworn holy matrimony? Have you verbally agreed to committed relationships?
Would you be in the right if you texted any of them and said, "Hey, if you're texting any other guys right now, I need you to stop."?
A date is not a commitment. A phone number is not a commitment. A text conversation is not a commitment. Having sex is not a commitment.
I'll skip the benefits of plate-spinning, as there's plenty of content there that seems like you've read up on. Sounds like you're hung up on the social aspects/what's "right" and "wrong".
Keep three things in mind:
1) Women take FAR longer than men for their interest in you to fully bake. No matter how high their interest level is in you, it takes time for them to really "become sold". You might instantly determine a woman is very attractive and that you're dead set on pursuing her. A woman, however, has been conditioned to slow things down. They don't even understand this need and try to rationalize it using phrases like "process my feelings" or "figure out how I feel."
2) In the beginning, women are ready and willing to drop you in a heartbeat. You're still a nobody in the book, just a "potential."
3) Don't believe Hollywood romance, but you've been told that a million times. How ever, think back to every chick flick or romance movie you've seen. Can you recall the last time you saw one where the woman was not tasked with choosing between at least two different men? This tells you something: women expect to choose, and they expect to be chosen. The only "romantic lovestory" is the dialogue between her and the ultimate winner of the **** race. All the losers were just irrelevant orbiters. This is the reality for women, so try to understand it's perfectly normal and even expected for you to be talking to multiple women when you are not in a committed relationship with any of them.