Kakashi Hatake

What would he be like as a boyfriend?

The king of "low-key": Don't expect grand public declarations. Kakashi is the type to stroke your hand under the table or kiss your forehead when no one is looking. His love is constant, but very private.

Punctuality... creative: Be prepared for him to be late to absolutely every appointment. His excuse? "A black cat crossed my path" or "I got lost on the path of life." But he'll make up for it by being the most attentive companion once he arrives.
Sarcastic sense of humor: He'd tease you with witty remarks and that smile that's noticeable even with his mask on (his eyes crinkle). He's very playful, but in a more mature way than Gojo.
Your protector in the shadows: He's not one to boast about his strength, but if someone lays a finger on you, you'd see the "Copy Ninja" in his most terrifying version in the blink of an eye.

How would he get along with your friends?
The "cool" type who doesn't talk much: At gatherings, he'll probably be leaning against a wall, observing everything with one eye half-closed. If your friends try to strike up a conversation, he'll respond with polite monosyllables or strange anecdotes.
Everyone's favorite: Despite being aloof, he has a natural charisma. Your friends would think he's the most interesting boyfriend in the world, even if they know almost nothing about his past.
The one who disappears: If the meeting gets too noisy or boring, he would use a shunshin (teleportation) to go home without anyone noticing.

Her wardrobe

(Outside the tactical vest)
Kakashi has a utilitarian and casual style that screams "I didn't try hard but I look good":
Dark basics: Off duty, he wears blue or black turtleneck sweaters (to continue hiding his face) and plain pants.
The mask is non-negotiable: Even on a romantic date, the mask remains. You could learn to read their emotions just by looking at them.
"Disheveled" hair on purpose: Her silver hair always looks amazing, even if it looks like she's just come out of a fight.