Jack Kornfield tweeted: "Everything that has a beginning has an ending. Make your peace with that and all will be well.” The Buddha taught that all conditioned phenomena are impermanent, that all meeting ends in parting. A Zen master put it simply: "Everything breaks. Attachment is our unwillingness to face that reality." 
I recently read these wise words: "We suffer, and make others suffer, when we try to hold onto things after their time, whether it’s relationships, experiences, or just the previous moment. Accepting their true, transient nature eases our fears, opens our hearts, and benefits ourselves and others. Non-attachment is neither indifference nor self-denial. Letting go of attachment is the secret to really enjoying life and loving others. It is freedom."