I'm going to open my relationship in an effort to sabotage it.
Why do you want to sabotage your relationship?
I would rather be with someone else.
Instead of sabotaging your relationship, you should talk to your partner and explain how you feel about them. Giving you both a chance to communicate will allow you to move on amicably and without resentment.
I think my partner will consider it. It seems like a great idea.
Most people will not be open to an open relationship. They don't want to have to compete for your affection. Please just break up and don't hurt your partner any more.