I agree that this dream does not probably have any deep spiritual meaning -- it is just your mind exploring an option that is not available (or not appropriate) in your waking life. As ThunderBow says, you are having strong feelings about this person at your work, and your mind is creating this outlet for those feelings. The guilt you feel in the dream is important -- this is your subconscious telling you that you would feel guilty if you followed your attraction to this girl at this time.
Some people believe every dream is a visit to the afterlife, but I personally think this is unlikely. We can be very much in love and committed to one person and still have passing attractions to other individuals, and sometimes our mind works through these feelings in our dreams. It can be pleasant, but doesn't mean anything in terms of your waking life decisions and commitments.
Ultimately, man should not ask what the meaning of his life is, but rather he must recognize that it is he who is asked.
Viktor E. Frankl