1) Maurice Ravel's "Daphnis and Chloé", especially the second set (lever du jour/ pantomime/ danse générale) takes longing, yearning, tension and release to an extreme. Choose a recording where they did not leave out the choir! The Furtwaengler recording from March 1944 (label: Archipel) carries more energy than all the others I have heard. I can compare its unbelievable crescendos only to, er, an erotic encounter. Furtwaengler teaches everybody a thing about interpretation and even makes you forget the permanent coughs from the audience and the heavy overdrive of the recording equipment at the climaxes when the concert hall seems to come down. But do yourself a favour and buy a good contemporary recording, too, e.g. Kent Nagano's. Daphnis and Chloé makes you want to put flowers onto Ravel's grave. Quelle beauté! Quelle tendresse! Merci, monsieur Ravel!
2) Max Reger's very short song (or lied) "Aeolsharfe" (aeolian harp) opus 75 no. 11, sung by Fischer-Dieskau. A tiny little gem, German romantic sentiment triple concentrated.
3) The third ache generator is a tie between a) "Wind on Water" by Robert Fripp and Brian Eno (album "Evening Star") with its unforgettable, inspired e-guitar line; b) "Mirage" for cello, keyboards and e-guitar by Terje Rypdal and David Darling (album "Eos", label ECM) which is an idyll with focused energy and plenty of space; c) "Mannelig", an ancient Swedish song, sung by the great Lena Willemark on the album "Nordan"; d) "O sacrum convivium" for mixed choir by Olivier Messiaen (e.g. on the label Catalyst) with one final 45-second "aleluia" that floors even an agnostic like me; and e) some recurring moments of LaMonte Young's special version of the Raga Sundara, regrettably not published yet. Awesome and deeply moving just with its beauty.
Sorry for writing so much, but these are the gems from my 20 years of collecting music. Sharing them is important to me.