In Catullus 40 the last two lines say,
"Eris, quandoquidem meos amorescum longa voluisti amare poena."
Which translates,"You will be, seeing that you wish to love my love with a long punishment."
In these two lines meos amores is neuter instead of a specific gender. Some interpret this to mean he is refering to Juventus, but some say that he refers to Lesbia. Still, others say it doesn't matter because this poem is more about bashing Ravidius than who Catullus loves. Also, in Catullus 30 lines 7 - 10 say,
"certe tute iubebas animam tradere, inique, meinducens in amorem, quasi tuta omnia mi forent.idem nunc retrahis te ac tua dicta omnia factaqueuentos irrita ferre ac nebulas aereas sinis."
Which translates,"Certainly you kept ordering me to entrust my soul, hostile one, leading me into love, as though all things were safe for me. Also now you divert you and allow the winds and airy clouds to carry all your worthless deeds and words."
In this passage Catullus uses you and not he or she. This does not allow the reader to clarify whether or not the person he is talking to is Lesbia, Juventus, or some other person. Again, most people think he is refering to Lesbia and may allow this poem to be placed with all the other poems about Catullus breaking up with Lesbia. However, Juventus is still an option some people like to use because he mentions the winds and clouds carrying words and Lesbia's words wouldn't have mattered much in Catullus's time because she is a girl and they didn't receive much respect in their time and whenever Catullus does mention someone's words being carried it is almost always a man. You could compare this to Brokeback Mountain, which tells the story of two gay cowboys. Although, it is a little more obvious than Catullus 40.