I get why he would feel emasculated after losing a match, but he can still show affection to his boyish gf while striving for strength at the same time. You can't just put a relationship "on pause" and expect the other person to not feel a little dejected. He's lucky she's chill like that.
It's weird and kind of frustrating because in the same chapter, she's right that it's a silly reason to feel unequal over, and he realized for a moment that he's being selfish.
His weakness does
not rest in him losing a match or two. It's that his sense of self-worth/manliness/whatever is dependent on a random physical thing. If
that really were the important thing in love, then he should just give up. There will always be someone stronger/faster/w a bigger d*ck/whatever. She loves him for being him. And if he doesn't do the same for her, then he should bow out, too, because being in love with her being a competent judoka is not love.
Sure, they are young, but I'm not perfect, and I never thought
this stupid thing. And if
I could figure out this, then they should be able to, too.