Related Clues:

• Never-dying
• Not ending
• Lasting an eternity
• Immortal
• Like Shangri-la
• Never cut off
• Lacking vicissitude
• Type of triangle
• Opposite of ephemeral
• What love can be
• Not transitory
• Always existing
• Eternal ... and a hint to 19-, 34-, 42- and 55-Across
• Untouched by time
• Always here