Met under arch can be described using different synonyms depending on context. If it's referring to a romantic rendezvous, some synonyms for it could be meeting under the moonlight, rendezvous at twilight, love under the stars, or chance encounter at dawn. If it's referring to a secret meeting, some synonyms for it could be clandestine gathering, surreptitious rendezvous, covert meetup, or private assembly. Alternatively, if it's referring to a meeting place, some synonyms for it could be gathering spot, congregation area, rally point, or rendezvous point. Ultimately, the perfect synonym for "met under arch" will depend on the context and intended meaning.