horizon, shore, limit, bound
涯 centers on a boundary where land meets water: a shore or horizon. It extends naturally to any limit or bound, the edge of something.
涯 combines 氵 (water) with 厓, which likely contributes both sound and the idea of a cliff or edge. Together they suggest the water's edge, a shore or limit.
Water 氵 meets a cliff-like edge 厓: that meeting point is the shore, the horizon, the limit of the land.
For ガイ, imagine standing at the shore and seeing a guy at the horizon: guy -> ガイ, marking the edge of the water.
life; lifetime; career
a person without a single relative
circumstances; one's situation or lot in life
lifetime; one's whole life; all through life
one's whole life
public life; public career
horizon; distant land; skyline; heavenly shores; remote region
very far away; the heavenly shores
two places being far apart
a great distance does not detract from the feeling (relationship) of endearment; feeling as though a dear one faraway were living in one's close neighborhood
water's edge
to die (of a person); to have one's life come to a close
(customer) lifetime value; LTV
lifelong learning
lifelong education; continuing education; further education
(the) best of one's life; lifetime ...
lifetime earnings
limits; boundary; end