Why does Paris want to marry Juliet so soon?

In Act IV, scene i, Paris explains to Friar Laurence his rush to marry Juliet. He says it's because she is grieving too much over her cousin Tybalt's death. She has been spending too much time alone. Juliet's father, Paris says, thinks so much grief is unhealthy, and that a wedding—and a companion to be with—will help her to recover her equilibrium. Love, however, is not the primary motivation at the moment, at least not on Juliet's part, because, as Paris puts it, a person in mourning can't fall in love ("Venus smiles not in a house of tears"). He says,

Immoderately she weeps for Tybalt’s death,

And therefore have I little talked of love,

For Venus [love] smiles not in a house of tears.

Now, sir, her father counts it dangerous

That she do give her sorrow so much sway,

And in his wisdom hastes our marriage

To stop the inundation of her tears—

Of course, Paris has wanted to marry Juliet since the beginning of the play, so this reasoning about haste may well be a rationalization. Paris says to Juliet's father, when he decides on a Monday that Thursday will be the wedding day, that he would just as soon they married even faster.