In "The Last Ride Together," the speaker reveals his thoughts through this dramatic monologue. In the first stanza, the speaker reluctantly but somewhat gracefully (he thanks her) accepts that his relationship with his mistress is over.
Of course, he is reluctant to completely let go, so he asks her to go horseback riding one last time. In the second stanza, she considers it and agrees. In the third stanza, they embrace momentarily ("Thus lay she a moment on my breast") before departing. In stanza 4, he dwells on "past hope," a time when the two were together and he considers what their present relationship would be had he acted differently.
In dealing with the loss of his relationship with his mistress, he considers his failure and supposes that all men fail. This might give him some solace as if there is a comfort that others suffer similar fates. The speaker concludes that unlike that statesman, who has only a few lines of biography in some obscure text to remember him by, he (speaker) at least has this one last ride. In fact, in the 7th and 8th stanzas, the speaker rationalizes that he is better off than the poet, sculptor and the musician. They deal with words, clay and notes; the speaker prefers real experience (the ride). This is all part of getting over his mistress. He still loves her, but accepts his failure with the comfort that others have failed; and he, at least, has this last experience.
However, in stanza 9, he begins to feel depleted. He considers that it is all downhill from here, noting that even Heaven will not restore the bliss he once enjoyed. He is annoyed to have been given such heavenly experiences knowing that the future can never compare to the past. His only consolation is if this earthly bliss is a mere glimpse of what Heaven might be. Once again, he philosophizes away from dwelling on his failure and turns optimistic. He supposes that Heaven will be similar to his blissful experience, just greater in intensity, "Changed not in kind but in degree." And, of course, the more intense Heaven lasts forever.
There is a sexual structure to the poem, one which Browning may not have intended. And it is also unlikely that Browning intended "ride" to be a euphemism for sex. However, the speaker goes from despair to comfort, although never quite to ecstasy, to emptiness (the climax being over) to optimistic supposition. As a dramatic monologue, this poem lets the reader into the mind of a man who is trying to accept and understand failure, first in love, but then in philosophical and spiritual terms.