In our life, sometimes we develop the tendency of fixing our happiness to other person/thing/situation and as a result when that entity no longer remain with us we feel deeply sad. So we should try to not get over dependent on any thing 'other' than our own self. Be strong and try to let go! Make sure in this whole process, you don't become narcissistic. Love shouldn't die for others. As Maya Angelou says: "love liberates not confines". Liberate and get liberated:)