an old flame	sb one was once in love with
steal one's heart	to make sb fall in love with one
the man of one's dreams	an ideal man
head over heels in love	very much in love with sb
break one's heart	cause sb great unhappiness
change of heart	a change of one's feeling for sth/someone
wear one's heart on one's sleeve	to allow once feelings to be too obvious
see eye to eye	to agree about sth
all's fair in love and war	all actions are justified when there are feelings of love/rivalry
the bee's knees	the best
donkey's years	a long time
bury the hatchet	forget old quarrels
the apple of one's eye	sb one is most fond of
the black sheep of the family	a person strongly disapproved by the other members of the family
play hard to get	to pretend one is not interested in sb
be like putty in one's hands	easily controlled or manipulated
drive sb round the bend	annoy sb a lot
tie the knot	get married
in clover	live comfortable
blood is thicker than water	family relationships are the strongest