Hormomal changes can indeed trigger such a dream. From a Freudian perspective, we desire to fulfill possibilities we don't currently realize in our lives whether it's water for the thirsty, desire for release for the captive, or love for the empty. It could also represent a mechanism to prepare you for the role manifested by those hormonal changes. From a Jungian perspective, I watch for evidences of possible shifts later in life in which an anima becomes animus or vice versa. But perhaps this matters less when such archetypes become swallowed up in the course of individuation when the focus late in life rests upon awareness of the Self.
But I would ask this because you labeled this as a "vivid" dream: were you aware in the dream that it was, in fact, a dream? The issue of lucidity comes into play because you wouldn't just have to ask the meaning of a dream or why it should occur at all. In a lucid dream, you must ask why you made the choices in the dream that you did, and those speak as loudly as the subject matter of the dream itself. In other words, if you were lucid while engaging the dream, did you stop at tender expressions of affection because the man in the dream desired to go further and you did not? If so, was it due to your own ethical sense or was it due to your understanding that to surrender to such affections in a lucid dream would compromise a necessary detatchment resulting in loss of lucidity?
It would be easy to see the effects of hormones in conjunction with your emotional disposition. Generally, we transition out of a desire to live and present authentically, but often, there's more to uncover. We often have latent desires that we may not have previously faced including those which could arise as a result of hormonal triggers. We cannot rule out this emotive issue because dreams develop accordingly. All dreams consist of a resorting of memory traces, each bearing an emotive tag from the limbic system. The hippocampus connects closely to the amygdala (fight or flight) and other structures involved in distribution and redistribution into the cingulate cortex. Memory traces with strong emotional tags will tend to get resorted a lot, and when the Preconscious picks up on them in ways we don't yet understand, they come across vividly, even in a nightmare. But any desire can carry emotional tags that we may never have previously realized. Was the desire for a man someting latently true for you? Only you can determine that.
