Rin Itoshi

Rin Itoshi's displays of affection would be subtle, indirect, and predominantly actions rather than words, remaining true to her tsundere, reserved, and competitive personality.
How would you express your affection?
Discreet and intentional physical contact:
Don't expect effusive hugs in public. He'll show affection with small gestures: holding your hand when no one is looking, placing his hand on the back of your neck or head while walking, or leaning on you when he's exhausted after an intense workout.
Practical and attentive care:
He remembers specific details without admitting it. He'll buy you your favorite drink or snack "because he had change" or "because it was on sale," he'll remind you to put on a coat if it's cold, or he'll make sure you've eaten well.
Words with double meanings and "mild" sarcasm:
Their compliments will come disguised as gentle criticism or curt remarks. Instead of saying "I missed you," they'll opt for "You're late" or "You're too noisy," but delivered in a much softer tone than usual and while maintaining eye contact.
Priority and alone time:
For someone so obsessed with football and training, time is their most valuable resource. If they choose to spend their free time with you, let you join them while they train, or watch horror movies together, that's their greatest way of showing they care.
Silent protection and possessiveness:
He'll put his arm around your shoulders or position himself between you and the crowd if you're in a busy place. If he senses that something is bothering you or someone is making you uncomfortable, he'll immediately intervene with his usual intimidating presence.

Rin Itoshi in love would express his affection intensely, reservedly, and with profound loyalty, substituting sweet words with practical actions and constant protection. Although he would try to maintain a cold and indifferent facade, his love language would change drastically in private:

Obsessive attention to detail: They would remember your exact tastes, routines, and small needs without you even asking. If you're tired or sick, they'll magically appear with your favorite drink or medicine, pretending they "just happened to be passing by."
Affection without words: Don't expect grand speeches or sentimental displays in public. Opt instead for subtle gestures: holding your thumb instead of your whole hand, adjusting your scarf, or stepping between yourself and the crowd to give yourself space.
Possessiveness and silent jealousy: If someone tries to flirt with you, they won't make a loud scene like their brother Sae; they will simply approach you, mark their territory with the coldest possible stare, and interrupt the conversation sharply.
He includes you in his world: Football and his training are everything to him, so inviting you to watch him train, asking you to fetch him water, or staying alone with you analyzing matches is his ultimate show of trust and vulnerability.
Vulnerability behind closed doors: In his most exhausted or frustrated moments, you would be the only person before whom he would lower his guard, silently resting his head on your shoulder to recharge his energy.

A romantic relationship with Rin Itoshi would be intense, emotionally distant, and goal-oriented, defined by his obsession with soccer and his introverted personality.
Based on its canonical nature in Blue Lock, this is how that dynamic would develop:
Emotional toughness and barriers
Little verbal affection: Don't expect romantic declarations or compliments. Rin is quiet, curt, and prefers to express himself (if at all) with practical actions rather than words.
Initial distance: They find it extremely difficult to open up or trust anyone. Their defensive shell is very high, and they tend to keep people at a distance to avoid showing any sign of vulnerability.
Blunt language: Their usual way of speaking is direct and often cold or dismissive. Getting past that layer requires a great deal of patience.
Absolute priority: Football
You'll be in the background: His goal of becoming the best striker in the world and surpassing his brother Sae consumes almost 100% of his attention and energy.
Unconventional dates: He's not interested in crowded social outings. A "date" with him will likely consist of accompanying him to training, watching games, or other quiet, private activities.
Hidden side and connection areas
Shared interests: Off the court, Rin enjoys horror movies and mystical or scary themes. Watching these kinds of movies together would be one of the few relaxing moments we'd have with him.
Silent loyalty: If he truly accepts you into his life, he will become extremely protective and dedicated, even if he never openly admits it.
Respect for independence: He will value a partner who has her own goals and is not emotionally dependent on him all the time.