Rona Fried and Leonard Berkowitz from NYU made an experiment on students.
On student would listen to a piece judged to be soothing (Mendelssohn, opus 19, n°1), another to a piece judged to be stimulant (Duke's one a clock jump), and the last one a piece judged to be tense (meditations by John Coltrane).
After the audition, when the student would be heading home, the experimenter would ask for a favour(help out with an assignment ordered by someone from the U...).
With the absence of music, 60% would give a hand. After the Mendelssohn piece, 90% would consent. The stimulant piece didn't bring any noticeable improvment, while the tense piece would make the number of students ready to help drop to 15%.
Moreover, one knows that positive mood activated by external stimuli, favorises a social assistance, while negative mood doesn't.
Conclusion : music affects your mood, mood affects your choices. Music can reinforce social relationships.