Hi ThisOneGuy17 and welcome to ehealth:...You don't calm her down...If this is something that she wants, she will probably either have it with or without you...Some people have a desire to satisfy themself in every way possible...Others reach their ultimate joy with one person...Different strokes for different folks...
If she is that horny, tell her to get a Eroscillator Vibrator to "cool her tools"...That way she will both satisfy herself and keep her boyfriend...I wish you well...Take care....
Caroline