Disappointing, but J & I haven't been able to determine if that's due to our own prurient desires or if, in the final scene, the filmmakers truly fell short of their promise.
I know what you mean. Well... maybe. I had issues with the end as well. After, someone near me said, "Oh, I was a little sad that in the end they didn't", and I nearly screamed back, "A little sad? It's majorly depressing."
I felt like, because these two characters failed to do this, their whole lives from this point on where never really going to achieve anything. Ben was never really going to be happy in his marriage any more, and Andrew was never going to finish an art project. It felt like the remainder of their adult lives were going to be scarred by the failure to commit to this act.
That said, I do think Shelton, in taking it the direction she did, handled it well, and made everything believable. But yeah, I would've preferred humping.