one-way street

noun3

1. •
   A road in which traffic is allowed to proceed in only one direction.
2. •
   (figurative) Something that lacks reciprocity.

   • Romantic love is not selfless but selfish. Although real love is not altruistic, nor is it narcissistic – a 'me-only', one-way street relationship. — 2009
3. •
   (figurative) A course of action that cannot be undone.