Animals have been observed to engage in sex for social interaction, bonding, exchange for significant materials, affection, mentorship pairings, sexual enjoyment, or as demonstration of social rank. It's probably safe to say that bonobos are the most sex-crazed mammals of all time. For bonobos, sex is not only highly pleasurable, it is also an important social tool:

Sexual intercourse in the animal kingdom functions to enable reproduction. However, we now know that several species of non-human primates regularly engage in sex outside of the times when รขโ‚ฌยฆ