Sonnet 42

That thou hast her, it is not all my grief,And yet it may be said I loved her dearly;That she hath thee, is of my wailing chief,A loss in love that touches me more nearly.Loving offenders, thus I will excuse ye:Thou dost love her, because thou knowst I love her;And for my sake even so doth she abuse me,Suffering my friend for my sake to approve her.If I lose thee, my loss is my love's gain,And losing her, my friend hath found that loss;Both find each other, and I lose both twain,And both for my sake lay on me this cross: But here's the joy; my friend and I are one; Sweet flattery! then she loves but me alone.
One more note regarding our threesome:as third wheel, I've reason to be glum.But if two become onewe can all have our fun—I'm technically still getting me some.