Robert Graves - The Thieves

Lovers in the act despense
With such meum-tuum sense
As might warningly reveal
What they must not pick or steal,
And their nostrum is to say:
'I and you are both away.'

After, when they disentwine
You from me and yours from mine,
Neither can be certain who
Was that I whose mine was you.
To the act again they go
More completely not to know.

Theft is theft and raid is raid
Though reciprocally made.
Lovers, the conclusion is
Doubled sighs and jealousies
In a single heart that grieves
For lost honour among thieves.

Robert Graves

http://www.poemhunter.com/poem/the-thieves/