A dream of romance
A card and clarifier are not two-halves of a sentence (part 1, part 2). They are *one* sentence (4/Cups), said a different way the second time around to help you understand. (2/Cups). Though, apparently, that 2nd time around didn't get understood, either
The point is, the clarifier doesn't negate the first card, nor does it add to it. It just "clarifies" it. If someone asked you a question, which you answered, then they said, "I don't understand..." you wouldn't give them a different answer. You'd just give them the SAME answer said differently. Yes?
So both cards are saying the same thing, just in two different ways. To figure out what, see what they have in common. If you look at both, you'll notice that, in both cards, the person is gazing at something/someone as if fascinated or dreaming. 4/Cups he is gazing at that cup on the cloud, 2/Cups he/she is gazing at the other person. In both there is a "dream" of romance in what they gaze at--but that doesn't mean that it is or can be a reality. In the 4/Cups especially, the message is that they may ignore something real for a fantasy. And in the 2/Cups, they are enthralled with that first impression of the person, but that doesn't mean that will pan out when they get to know said person better
Which is to say, her attraction to him, both cards say, is not rooted in reality and may be because she is bored. At best, she's imagining what romance with him would be like, nothing more. And yes, she probably is dissatisfied with her current relationship, but the 2/Cups doesn't mean she's looking for anything deeper. It means she's just looking, as in the 4/Cups for something new or different. She could as easily become dissatisfied with your brother as she is with the man she's with now because she's after a *dream* of romance, not real love.