Who teases Romeo about rosaline and his love sickness?

Mercutio - his friend. Mercutio

Mercutio never stops teasing Romeo about this, even after Romeo has lost all interest in Rosaline. "He jests at scars that never felt a wound."

Romeo was in love with rosaline but rosaline was not in love with him back the love was unrequitted

It worked perfectly. Romeo was completely cured of Rosaline.

Rosaline is a young woman that Romeo loves, and makes Romeo devastated and heartbroken that Rosaline doesn't love him back.

At the opening of Romeo and Juliet, Benvolio teases Romeo about being in love with Rosaline. Romeo is having no success with Rosaline (and in fact he goes to the Capulet's ball because he believes she will be there). We do not know if Rosaline is Romeo's first love - for all we know he may have had many girlfriends before her. But she never appears in the play, and as soon as Romeo sees Juliet he forgets all about her. I thought that he went becasue his friend made him go!

He is only infatuated with Rosaline

He loves Rosaline, but Rosaline does not love him.

In Romeo and Juliet, Romeo first loves Rosaline, However, Rosaline has sworn to be chaste for life and never wants to marry. So, she will never love anyone.

At the beginning of the play Romeo first falls in love with Rosaline, a relative of Juliet, before falling in love with Juliet

Friar Lawrence thinks that Romeo has been with Rosaline instead of with Juliet because he doesn't know yet that Romeo has fallen for Juliet and does not love Rosaline any more. Romeo and Rosaline used to be lovers, but now that Romeo has met Juliet, he doen't love Rosaline any longer. Therefore, he assumes that Romeo has been with Rosaline for the night because he doesn't know that they are not in love any more.

his love rosaline does not love him back.

Last time Friar and Romeo talked, Romeo was so in love with Rosaline. Romeo does not love Rosaline anymore because he has since met Juliet.

Romeo was truly in love with Rosaline (even if "Romeo and Rosaline" don't sound as good together). Romeo was crushed when Rosaline dumped him and decided to stay a virgin for the rest of her life. He couldn't go on without the love of his love, Rosaline... then he met Juliet, and you know.

Romeo had hoped to see Rosaline at the ball. Rosaline was a girl that Romeo liked before he meet Juliet. Except Rosaline doesn't love Romeo back

Romeo has unrequited love for Rosaline but it's mutual for Juliet

The sight of Juliet makes Romeo fall in love with her therefore forgetting everything about Rosaline.

Benvolio doesn't seem to love anybody in Romeo and Juliet. In fact at the end of 1.1, and again at the beginning of 1.2 he seems to be teasing Romeo about being in love with Rosaline. But Benvolio's teasing is quite gentle - so perhaps Benvolio has been in love himself at some stage. Mercutio also teases Romeo about his love for Rosaline (2.1, and again at 3.1) - but Mercutio's teasing is vicious and obscene. Mercutio clearly has some kind of an issue with girls.

At the start of Romeo and Juliet, Romeo is in love with rosaline niece of Capulet.

He believes himself to be in love with Rosaline who will not love him back

They never hear about his real love. They just know about his crush on Rosaline, and Mercutio teases him unmercifully. Benvolio is much more sympathetic and offers practical advice on how to get over it.

Romeo does not like Rosaline anymore because his love for her vanished when the beauty of Juliet caught his eye.

At first Romeo liked Rosaline but when he saw Juliet at the party he completely forgot about Rosaline and fell in love with Juliet.

Romeo us moody over his unreturned love with rosaline

In love with Rosaline.