What is love?

Love - to have strong feelings of affection for another adult and be romantically and sexually attracted to them, or to feel great affection for a friend or person in your family.
Cambridge Dictionary

The traditional psychological view sees love as being a combination of companionate love and passionate love.
Passionate love is intense longing, and is often accompanied by physiological arousal (shortness of breath, rapid heart rate).
Companionate love is affection and a feeling of intimacy not accompanied by physiological arousal.

Hymn to Love
If I speak in the tongues of men and of angels,
but have not love,
I am a noisy gong or a clanging cymbal.

And if I have prophetic powers,
and understand all mysteries and all knowledge,
and if I have all faith, so as to remove mountains,
but have not love,
I am nothing.

If I give away all I have,
and if I deliver my body to be burned,
but have not love,
I gain nothing.

Love is patient and kind;
love is not jealous or boastful;
it is not arrogant or rude.
Love does not insist on its own way;
it is not irritable or resentful;
it does not rejoice at wrong, but rejoices in the right.

Love bears all things,
believes all things,
hopes all things,
endures all things.

Love never ends;
as for prophecies, they will pass away;
as for tongues, they will cease;
as for knowledge, it will pass away.

For our knowledge is imperfect and our prophecy is imperfect;
but when the perfect comes, the imperfect will pass away.

When I was a child,
I spoke like a child,
I thought like a child,
I reasoned like a child;
when I became a man,
I gave up childish ways.

For now we see in a mirror dimly,
but then face to face.
Now I know in part; then I shall understand fully,
even as I have been fully understood.

So faith,
hope,
love
abide, these three;
but the greatest of these
is love.

Chapter Thirteen of St. Paul's First Letter to the Corinthians

Hymn to Love from Kieslowski Bleu Film

The Love Movie

What is Love? by Associated Content

So I guess romantic love is: 1) passionate love making - giving the highest conceivable pleasure to your darling and 2) watching a movie together covered with the same blanket making sure that your loved one’s feet are not sticking out.

Oh, this is a good one:
"You know you're in love when you can't fall asleep because reality is finally better than your dreams.” Dr Seuss