My opinion on cheating on people ...

Just don't do it.
It's cruel, selfish and immature.
Trust is an important factor that plays into my relationships and once that is ruined it's difficult for me to be open with those who have broken that bond.
I feel like if you're really thinking about being with someone other than the person you are committed to don't be selfish and try to keep two people in your life.
Put on a pair of big boy/girl pants on and choose what you want.
Don't drag someone who cares about you and thinks you care about them down a crappy path.
Even though it will probably hurt that person like hell to hear that you've found someone else, maybe they'll still have an ounce of respect for you because you were honest and didn't betray them by cheating.
Yes, your significant other may be driving you crazy and you're not as happy as you used to be, but if you are really that unhappy then just end things.
Save yourself the stress of starting a crazy soap opera that stars you, someone who probably still loves you and some other person you've got eyes for.
There's enough lying and disappointment in this world so be a human and have a heart and just don't be a cheater. 
That's all I have to say about that.