if only
guilt
regretfully
regretting
lamentably
fear
regrettingly
apologize
may the Force not be with you
regretlessness
shame
whip the cat
ruesome
regret
may the Force be with you
regrettable
regrettably
pity
too bad
live to regret
regretter
eat one's words
Ichabod
look back
nostalgize
bon voyage
I'm afraid so
seem like a good idea at the time
resipiscence
could have, would have, should have
nostalgism
all the best
no such luck
repathologize
compunction
for old times' sake
self-reproach
wear sackcloth and ashes
remorse
rue
repent
regrettableness
bummer
sorry
whoops-a-daisy
rest on one's laurels
whoopsie-daisy
send back
rue the day
roll back the years
God be with the days
may the odds be ever in your favor
reminiscential
oh well
deplore
bemoan
take back
wishful thought
bewail
F
lament
nostalgia
nostophobia
semiapologetic
contrite
regretfulness
nostalgically
pastism
repentingly
pastness
regretful
sorriness
misremembrance
dream
had
promised
plea
precedent
forgiving
sayang
for shame's sake
bring back
may
ain't what it used to was
repine
alack and alas
reacknowledge
old times
reacceptance
langsyne
auld langsyne
lang syne
pitch and toss
good old days
remythologize