注孤生：doomed to be forever alone./doomed to leada lonely life.
备胎：back burner 吃回头草：reconcile
单身狗：bare branches/ unattached/ bachelor
1）注孤生：doomed to be forever alone./doomed to leada lonely life.
eg:He is doomed to be forever alone./He is doomed to lead a lonely life.
eg:He rarely talks to me these days, do you think he's just being busy?
I think he's back-burnering you.
eg:He has recently reconciled with his ex-wife.
4）单身狗：bare branches/ unattached/ bachelor