I'm thinking of cheating on my boyfriend.
Are you for real? Why would you cheat on your boyfriend?
I love him, but our sex life is extremely boring
It's understandable to expect an exciting sex life with your partner, but significant others are expected to be faithful to one another. Cheating on them will just break their heart. If you're unhappy in the relationship, then break up with them and find someone appropriate for your sex drive.
I'm getting bored in the relationship, so I want to sleep with someone else.
You should just leave him before you do this, this is going to break his heart.