Contact is defined as the coming together of three factors; the organ of sense, the external object and consciousness. It is symbolized here by one of the most intense occurences of contact; a couple making love.
Contact is the process by which consciousess accesses the external world. Here we are peeking through the windows of the last image. Contact occurs again and again without cessation throughout a lifetime.
Remember that in Buddhist theory, there are six senses. The mind-sense is that which contacts objects of the mind (thoughts etc.) So even when there are no external sense impressions, contact is still occurring.