In addition to the dramatic irony of Lord Capulet's irate threat to his daughter Juliet to "never look him in the face again" about which the audience has been made aware in the Prologue will come true, there is the verbal irony of Lord Capulet's lines. In his anger, he indicates how his and Lady Capulet's regret, "That God has lent us but this only child,"has become a different type of regret. Then, he adds, "And that we have a curse in having her." However, it is dubious that Lord Capulet really feels that Juliet is a "curse," at least not to the extent of what will soon occur. Above all else, it is the situational irony, or the disparity of Lord Capulet's intentions and the result, that is the most profound. For, in his berating of Juliet, Capulet only intends to make her obey him or leave their home, not die.
This passage too, presents an irony of theme, as well as the theme of "Youth vs. Age" is subverted as Lord Capulet becomes, ironically, the more impetuous and irrational in his relationship with his daughter Juliet. Indeed, this passage from Act III of Romeo and Juliet is replete with irony.
I tell thee what—get thee to church a Thursday(165)
Or never after look me in the face.
Speak not, reply not, do not answer me!
My fingers itch. Wife, we scarce thought us blest
That God had lent us but this only child;
But now I see this one is one too much,(170)
And that we have a curse in having her.
Out on her, hilding!
Shakespeare's dialogue is full of irony when Lord Capulet makes this angry retort to Juliet's insistence that she will not marry Paris. Capulet's warning to Juliet "get thee to church on Thursday or never after look me in the face" will later prove ironic, because Juliet's refusal to marry Paris ultimately causes her to take part in the plan to fake her death which will lead to her actual death.
Like her father strangely predicts, Juliet does not go to the church on Thursday to marry Paris, and true to his word, she never looks him in the face again, just not for the reasons that Lord Capulet originally thought. The father's words here spoken in haste will be much regretted later; Lord Capulet does love Juliet, but as a man who is used to having his way, he is easily frustrated by what he perceives as the whims of his teenage daughter.