be/fall head over heels in love	be very much in love with sb
wear one's heart on one's sleeve	allow one's feelings to be too obvious
see eye to eye	to agree
all's fair in love and war	all actions are justified when there are feelings of love or rivaly
be the bee's knees	to be the best there is
donkey's years	a long time
bury the hatchet	to forget old quarrels
the apple of sb's eye	sb is most fond of
play hard to get	to pretend one is not interested in sb
like putty in sb's hands	easily controlled or manipulated
drive sb round the bend	to annoy sb a lot
tie the knot	to get married
in clover	in comfort
blood is thicker than water	family relationships are the strongest
an old flame	sb one was in love with