In vamachara or the left handed path tantric sex involves yoni worship. It is not 2 bodies coming together but that of two energies kaal and kali. There are infinite number of paths to approach the infinite. The seeker of the truth will see it everywhere. A seeker of the truth and the bodhisattvas(destined for enlightenment) can take any path and will not be adamant about just one path ! Shiva worship is nature worship. Be focused , be present especially with your loved one ! tan tra is experience. Love is worship !