cipher - Why Do You Love Me?

^{An entry in Fortnightly Topic Challenge #35: Restricted Title 1.}

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I met an amazing girl today. Not only is she smart and share my love for art, she also really like puzzles! However, when I asked her out on a date, she smiled and gave me this piece of paper, saying "Solve this and meet me! First one should be as easy as buying salad dressing." I've been struggling over them, but perhaps you can help me score a date?

ONE

H THU HUK H DVTHU ZAHUKPUN AOL THU PZ OVSKPUN H MHYT LXBPWTLUA UPJL OVBZL PU AOL IHJRNYVBUK

TWO

AZMTMGVRTWGNQPABEIQUINTWLSIPDNIWWTEZUBWHG

THREE

CZIB FHMO N VSDR CIG O SBYIXDLCR DBI DTGS PRRTUE

FOUR

B EMRM KO FWJ BEIP TTX

FIVE

OEXXZLAQLMNRRFAIGVHKFIXABYAHVWIGXPJNHBG :)

Love,

Hannah

Answer

The messages have to broken in order, as each one helps clue the key to decrypting the next.

ONE

The reference to salad dressing indicates that this is encoded with a Caesar cipher or rotation cipher. Running through the values, we find that rotating each letter back seven places in the alphabet gives this:
A MAN AND A WOMAN STANDING THE MAN IS HOLDING A FARM EQUIPMENT NICE HOUSE IN THE BACKGROUND

TWO, given ONE

The deciphered text from ONE is a reference to the Grant Wood painting American Gothic. Decrypting this text as a Vigenere cipher with key "AMERICAN GOTHIC" gives:
ANICEEVENINGINAPARISIANISLANDBEFOREMONDAY, that is
A NICE EVENING IN A PARISIAN ISLAND BEFORE MONDAY

THREE, given TWO

The deciphered text from TWO is a reference to the Georges Seurat painting A Sunday Afternoon on the Island of La Grande Jatte. Decrypting this text as a Vigenere cipher with key "ASUNDAYAFTERNOONONTHEISLANDOFLAGRANDEJATTE" gives:
CHOO CHOO I COME OUT A FIREPLACE AND STAB PEOPLE

FOUR, given THREE

The deciphered text from THREE is a reference to the René Magritte painting Time Transfixed. Decrypting this text as a Vigenere cipher with key "TIMETRANSFIXED" gives:
I WANT TO SEE THEM ALL

FIVE, given FOUR

The deciphered text from FOUR is a reference to the fact that all four mentioned works of art are part of the permanent collection of the Art Institute of Chicago. Decrypting the final text as a Vigenere cipher with key "ARTINSTITUTEOFCHICAGO" gives:
ONEPMTHISSUNDAYBYTHERIGHTLIONDONTBELATE :), that is
ONE PM THIS SUNDAY BY THE RIGHT LION DONT BE LATE :)
As you can see on the linked Wikipedia page, the Institute's main entrance is flanked by two bronze lion statues. With your meeting time, meeting place, and date planned out, you should have lots of time between now and then to prepare.
If you want to make a good impression, I'd recommend reading up a little on some more famous pieces you might see there; there's quite a lot.