affinity, relation, connection, edge, border, verge, brink
縁 centers on the idea of a link or boundary: a connection or relationship that ties things together, and the edge or border where something meets something else. The edge sense is the physical boundary, while affinity and relation are the abstract ties.
縁 combines 糸 (thread) with a phonetic component that also suggests connection or following along. The thread radical reinforces the idea of ties and relationships, while the edge meaning likely developed from the idea of a hem or border.
Threads 糸 are used to sew edges and bind things together, creating both physical borders and relationships.
For エン, imagine the end of a thread tying a connection: end -> エン, and the thread creates the edge.
rim; brim; edge; brink
connection (to a person, place, etc.); relation; affinity
unrelated; unconnected; irrelevant; indifferent; divorced from; having nothing to do with one; being foreign to one
omen; sign of luck
reconciliation (with one's spouse, adopted child, etc.)
fate; destiny
breaking off relations (with); severing one's connections (with); breaking with (e.g. one's past)
blood relationship; consanguinity
forming a familial relationship (through adoption, marriage, etc.)
(picture) frame
temple festival; fair; fete day; day related to a particular deity and thought to bring divine blessing to those who celebrate it
engawa; external corridor on the outer side of traditional Japanese houses
marriage; marriage tie; love knot
relation; connection; affinity
marriage proposal; marriage talks
(undesirable but) inseparable relationship
talisman; lucky charm
curb (stone); kerb
relative; relation
de facto marriage; common-law marriage