I think this is about longing for uncompromising love, and I would interpret uncompromising love not as some form of selfishness, but on the contrary as a love that is not diminished by reason, personal needs, obstacles.
The sadness comes from feeling disconnected to this love in which the subject of the poem anyway believes.
Waves of unknown oceans, harvesting the sea gives me the impression of something that goes deeper than an orgasm, some transcendent unity (i don´t find the right words).
Lines of red wine pouring from gashes maybe means that love hurts only because we don´t handle it with enough care. Maybe we are not able to because we misunderstand the idea of love.
Well, this is probably not what Mr. Tankian wanted to express, it s just the thoughts the poem caused in me.