friend zone

Short definition from Wiktionary

Noun

1. 1
   The situation in which one is viewed by a potential partner as a platonic friend, which complicates the initiation of a romantic relationship.
2. 2
   Alternative form of friend zone.

Verb

1. 1
   To classify (someone) as a friend, without any possibility of a romantic relationship.
2. 2
   Alternative form of friend zone.