It’s time to duew! X3

He ends up trying to filter the idea of love through a lens of power and victory because those are the ideas of measurement and value he has. He's also trying to understand love through battle and fighting -- to fight for something.

"Can a person be strong when they are shouldering the weight of protecting somebody" can cut a few possible ways. Seto taking the brunt of Gozaburo's abuse instead of Mokuba may be something Seto felt "strong enough" to take, but sharp bitterness and mistrust seeped into him like a poison at some point.

It's also that Seto was observing Yugi's friend group during Death-T, studying it in a way. He'd expected them to turn on each other at some point, perhaps hoping for confirmation bias on some level, but Seto's ongoing relationship with Gozaburo left him with maladaptive coping mechanisms he'd prefer to view as strengths he chose to take into his hands.

Desperation and sadness suddenly engulfing him are how Seto's feelings of love reveal themselves in practice, when "fighting" wasn't enough. The love is there with his failure. It's not about gaining victory as showing love. Love is just there, but I don't think Seto is especially conscious of that.

But fighting and battle are how Seto communicates. He instigates these situations of communicating in his duels.

Seto on his own brings up discussion of his angry history and memories on a few different occasions while on Alcatraz in the manga. Some part of him wanted to talk about it but I think if this was pointed out to him, he'd possibly get defensive because suddenly he'd be aware of how the others were reading into this. Very teenage angst, that back and forth in his head.

He seems to have a fluctuating sense of emotional empathy as well and is surprised when it stabs him in the heart. He's fairly eager to tuck that part of himself away. There's also the aspect that Seto was attempting to communicate something to Gozaburo through their "battle" but it's vague -- I don't think Seto in canon would be able to pin it down, those feelings are too stormy and foggy in the aftermath, and I think canon itself being vague has a sort of realism in a way.