We're not going to lie to you, Shmoopsters. Following our heartbroken speaker's train of thought can be a little tricky in this sonnet. His math skills are seriously questionable (line 8, we're looking at you here). Plus, the dude LOVES him some metaphors and sometimes those metaphors can be a little hard to follow.
Take, for example, the time he imagines his mistress' heart is a jail that's holding him prisoner (9) and then goes on to say that his own heart's a little jail, too, and that it's going to "guard" his friend's heart from his cruel mistress (10-12). Wait a minute. Does that even make sense? If you love someone, why would you want to put them in a jail within a jail (even the metaphorical kind)?
Slightly confusing? Yep. Does the metaphor make perfect sense? Nope. But, guess what? Being in a complicated love triangle with your girlfriend and your BFF can be pretty confusing, too, especially when you try to describe the three-way relationship in a sonnet. Hmm. Maybe that's the point.
So, if you find yourself feeling a little baffled and annoyed with Sonnet 133, consider this: maybe Uncle Shakespeare wants the experience of reading this sonnet to feel like the confusing and chaotic emotional experience of being tangled up in a messy relationship.