Synonyms for Rift:

n.

channel, crater, cavity, aperture, blowhole, fissure. disagreement, dispute, fight, argument, misunderstanding, confrontation, conflict, a war of words, controversy, quarrel. open, cleavage. help, rent, assemble, schism, disaffection. smash, splinter, shiver, rive, shatter, sunder. aperture (noun)
cut, gash, chasm, slit.
blemish (noun)
fleck, scrape, stain, flaw, fracture, sore, slit, scratch, weal, brand, mar, spoilage, hack, imperfection, distortion, pockmark, freckle, splotch, fault, disfigurement, check, gash, kink, chip, discoloration, drawback, speck, eyesore, damage, tarnish, wart, score, blotch, deformity, scar, nick, blemish, blister, stigma, hurt, abrasion, scab, impurity, dot, defect, notch, defacement, lesion, scuff, blot, spot, mark.
breach (noun)
chip, disaffection, aperture, severance.
break (noun)
fight, dispute.
breakup (noun)
divorce.
chasm (noun)
crater, gulf, cavity, ravine.
gap (noun)
crevice, gap, interval, space, breach, chasm, cleft, break, ravine, gulf, abyss.
notch (noun)
incision, chink, indentation, serration, cut, indent, jog.
opening (noun)
split, chink.
rift (noun)
falling out, cleavage, severance, quarrel, fault, fissure, fracture, alienation, chink, division, break, gap, space, rupture, rent, disagreement, breach, crevice, flaw, cleft, misunderstanding, estrangement, split, interval, separation, schism.
separation (noun)
isolation, separation, division, divorce, split, segregation, alienation, estrangement.

Other synonyms:

rive, cleavage, shatter, splinter, fissure, schism, smash. disaffection. channel. Other relevant words:
disaffection, cleavage, cavity, aperture, controversy, fight, quarrel, crater, channel, dispute, splinter, argument, falling out, shatter, conflict, help, chink, rupture, confrontation, open, disagreement, schism, severance, shiver, assemble, fissure, rive, smash, blowhole, rent, sunder, misunderstanding.