tree ke paas kal milenge and sweet romantic songs gayenge( a thick sweet liguid is treacle) anf this is treacly.( overly sweet) in false way.
think of treble.. which is the part of sound that produces a sweet effect!
treacle - always like tweety-sweety, or always giving a treat of sweets
treacle = tree + acle; The sweet made from acle means original tree juice.