Develop a musical piece that combines the given theme and letter-structured outline.
X:1
L:1/8
M:6/8
K:D
['d2 B cBA dAF', 'd2 f afa', 'def def dAF']  
X:1
L:1/8
M:6/8
K:D
 d2 B cBA | dAF FED | d2 B cBA | dAF EFA | def Bcd | ABA F2 E | DED DEF | AFE EFA :| d2 d fdf | 
 aba afe | d2 f afa | bge edB | d2 f afa | bgb a2 f | fed def | dAF EFA :| def def | dAF DFA | 
 def def | dAF E2 A | def Bcd | ABA F2 E | DED DEF | AFE EFA :|  