Obviously not chimpanzee females. They like their man to share a bite with them once in a while and they'll never forget him for it.
Males are just regular joes, they see this transaction as an investment. I give you some meat, you give me "love".
Chimpanzee males are apparently so patient, that, not only do they offer meat to sexually receptive females, but also to those who have not responded to their advances yet.
They're thinking long term investment.
This has now been documented in a paper written by two primatologists from Leipzig, Germany, Cristina Gomes and Christophe Boesch.
More info at the Science Now website in this article: Chimps Trade Meat for the Chance of Sex.
You may also remember an article written by Michael Gumert (see post from January), that demonstrated a similar practice among long-tailed macaques.