How I see it...
If you are even contemplating exploring other options while in a "committed" relationship, then there is something missing with the current relationship..
So, what is missing or lacking in the current relationship that is sparking interest in exploring other options?
Is there anything you or your current significant other could do to rekindle the spark that got y'all together in the first place?
If you were to explore other options, leave the current significant other and get with someone else, do you think it would pan out? What if the grass isn't greener on the other side and you find yourself in the same situation as the former relationship? Then what?
It comes down to this..
Life is about taking chances. I will not say that someone has to stay with their current situation, if said person isn't happy, but I am not sure if hopping from relationship to relationship is the solution..
If anything, I would say that if you genuinely care about your current situation, but something is missing, then perhaps it may be best of you exhaust all options with that person before exploring other options, but if you do decide to explore other options, then give your current significant other the courtesy of letting him/her go so they can do the same and let the chips fall as they may...
Just keep in mind that should you let your current significant other go, that you may not get that person back, should things not work out in your favor with the new person(s)...