No one else could have understood the bond between the two stepbrothers, but the pair in question had never thought anything of their uncanny ability to understand each other without conventional communication. And so, as always, Ferb didn't even have to open his mouth to convey exactly what was going on in that spectacular brain hidden beneath the shock of emerald green hair. He only had to raise one fine eyebrow in a precise manner to make his inquiry known.
"It's nothing," Phineas replied to the unspoken query, his agitated pacing of the room belying the dismissal. "Ever since I broke up with Isabella, I've felt kind of bad for her, but I don't feel bad, you know? I always thought that nobody is supposed to be happy after a breakup, but I feel..." He paused thoughtfully, searching for the right term.
"Relieved," was the offered completion to the statement.
Phineas lit up. "Yeah, relieved." He finally plunked down onto the edge of his bed. With a sigh, he buried one hand in his hair and struggled to find the correct words to assess the situation. Emotions were not exactly his forte, specifically those pertaining to the female gender. "I didn't feel like it—I mean the relationship—was... right. It's hard to explain."
Ferb's even gaze shifted almost imperceptibly, but Phineas was able to draw on the look of understanding in his brother's features. But slightly more disturbing was the knowing look in Ferb's jade eyes. His expression indicated that he knew far more about the reason for the breakup that Phineas had ever confided in him. In that moment, Phineas was at a crossroads, stuck between finally divulging the emotional storm that had been brewing for ages or continuing the charade in hopes of ignoring it all. Of course Ferb wouldn't judge... Ferb was his brother, his best friend, his partner in—well, if not crime, then the breaking of physical laws! It was a secret Phineas had been keeping for too long, and if he could just work up the courage, then—
"Just tell him," Ferb said out of the blue, interrupting Phineas' mental debate.
And of course, of course, the default response that came out of Phineas' mouth was "I don't know what you're talking about."