1593-1603 by Shakespeare 
Sonnet 42 

1	That thou hast her, it is not all my grief,
2	And yet it may be said I loved her dearly#
3	That she hath thee is of my wailing chief,
4	A loss in love that touches me more nearly.
5	Loving offenders, thus I will excuse ye:
6	Thou dost love her because thou know’st I love her,
7	And for my sake even so doth she abuse me,
8	Suff’ring my friend for my sake to approve her.
9	If I lose thee, my loss is my love’s gain,
10	And losing her, my friend hath found that loss:
11	Both find each other, and I lose both twain,
12	And both for my sake lay on me this cross.
13	But here’s the joy: my friend and I are one.
14	Sweet flattery! Then she loves but me alone.