With Sonnet 120 William Shakespeare draws a line under the explanations and excuses offered throughout the previous three sonnets for his own infidelities in relation to his young man, and simply reminds himself now of how awful he felt when his lover treated him in a similar way on those occasions when it was him who was sleeping around with other people. The conclusion Shakespeare comes to is that they both in turn have been through hell, and that their respective debt to each other for each other's transgressions now must surely cancel itself out.

With Sonnet 119, William Shakespeare further elaborates on his metaphor, introduced in Sonnet 118, of having taken bitter medicines to prevent himself from ever getting sick of his younger lover, these potions having been affairs, encounters, or even relationships of sorts with other people.

Who these other people were he still doesn't tell us, but he here makes it even clearer that they were fundamentally bad for him, their principal, if not sole, redeeming feature being that their experience has ultimately strengthened him and cemented his love for his young man.
​The sonnet is the third of three sonnets which all attempt to explain and to some extent excuse Shakespeare's infidelities of the past, and they all do so in the wake, directly, of Sonnet 116 which famously and categorically posited, "Let me not to the marriage of true minds | Admit impediments."

Sonnet 118 continues William Shakespeare's defence or explanation of his infidelities towards his younger lover with an argument that may well strike us as similarly spurious as the one deployed in Sonnet 117, even though unlike the previous poem, this one possesses an internal logic that allows him to come to a conclusion which does make some sense: so as not to get sick and tired of you, I have been tasting some bitter 'appetisers', as we might call them today, even going as far as purging myself with medicinal concoctions to ward off any such 'illness', but what I found in fact was that these 'treatments' themselves turned out to be harmful to my health and wellbeing.