My actual series, where the books are linked by premise and plot (as well as the order you should read them) are:

ABSOLUTELY PERFECT
ABSOLUTELY WONDERFUL
ABSOLUTELY MINE

HAPPILY EVER AFTER
LOVE EVER AFTER
MERRILY EVER AFTER

CAD’S WISH
CAD’S PICK
CAD’S CHOICE

SOMEONE TO LOVE
SOMEONE TO CHERISH
SOMEONE TO WED

MY SCOUNDREL (previously released as NICHOLAS)

ALWAYS
ALWAYS YOURS
ALWAYS MINE

JILTED BY A CAD
JILTED BY A SCOUNDREL
JILTED BY A ROGUE

FOREVER YOURS
FOREVER MINE
FOREVER AFTER
FOREVER

ONLY YOU
ONLY MINE

HEART’S DELIGHT
HEART’S DESIRE
HEART’S DEMAND
SCOUNDREL
HEART’S DEBT

WICKED
WANTON
WONDERFUL

LOVE’S PROMISE
LOVE’S PRICE
LOVE’S PERIL

SEDUCE ME
KISS ME
LOVE ME

My linked books have a connecting premise or subsidiary characters that bind them together, but they aren’t official trilogies. My linked books and the order you should read them are:

PROMISE OF PLEASURE
TASTE OF TEMPTATION
DREAMS OF DESIRE

LOVE LESSONS
TOTAL SURRENDER

DEEPER THAN DESIRE
MORE THAN SEDUCTION

COMPLETE ABANDON
FORBIDDEN FANTASY

TOO WICKED TO WED
MY ONLY LOVE
MY TRUE LOVE