In Romeo and Juliet, why does Paris not appear at the Capulet party after agreeing with Lord Capulet to woo Juliet there?Did Paris actually meet...

In Act I, scene ii, we learn that Paris is interested in
marrying Juliet, and that Capulet warms him that it will not be wholly his choice, but
that Juliet herself will have a say -- a very unusual position for a father to take in
Shakespeare's day.  Capulet does invite Paris to his
party:

This
night I hold an old accustom'd feast

Whereto I have invited
many a guest

Such as I love, and you among the store. .
.

He actually goes on to
encourage Paris to look over all the girls who will be there to "like her most whose
merit most shall be," cautioning Paris that Juliet is but "one" of many young ladies who
will attend, indicating that Capulet is not so sure that this match is a good
one.

In the party scene itself (Act I, scene v), Paris does
not have any lines, but you should be careful not to assume that this means he is not
onstage.  Shakespeare, like any playwright, understood that the staging of any scene
involves much more than just the speaking of lines written.  Consequently, Paris'
appearance at the party and his potential interaction with Juliet is up to those staging
the play.  Juliet is actually talked about by Romeo before they meet.  Does he, for
example, describe her as she is in private conversation with Paris?  This sort of
decision, again, is up to those staging the play.

Paris,
then, is very likely at the party scene, and also, potentially, actually interacting
with Juliet.  All of this is not scripted by Shakespeare, however, and is meant to be
constructed during the staging of the play.

It is also
worth noting that Romeo attends the party because he sees Rosaline's name on the list
which Capulet's servant has him read earlier in Act I.  She is also not a "speaking"
character in this scene, but her presence onstage just as likely as that of
Paris.

For more on Act I, scene v, please follow the links
below.