His eyes glowed a glow that warmed my very soul. He smiled and I found myself smiling back, because his smile just has that effect on me. It's said that the eyes are the windows to a person's soul...I saw unconditional love, happiness, and truth in his eyes at that very moment. I knew, before he even said it what he was about to say:

 "I love you, Kari."

In answer to your question, there will be quite a few signs, but they may vary.

• When you look into his eyes, they will glow and/or sparkle with emotion when he looks at you.
  
• When he smiles, it will reach his eyes and you'll be able to tell it's a true smile, not a fake.
• His touch will be softer, gentler, more of a caress.
• He will go out of his way to do things just to see you smile.
• He will wait 2 years to see you in person.
• He will say "I love you" in a soft, gentle, loving voice, while smiling that gentle smile that makes his eyes glow.
• Instead of using his money to buy video games, he'll buy you a little teddy bear for your birthday that he knows you'll love, even when you told him you don't want anything.
• He will buy you another little teddy bear for Christmas that's holding a heart pillow that says "Girlfriend" on it, and he'll kiss the heart before packaging it up and sending it to you.
• He'll risk getting caught texting in class because you're far away from home on a band trip and you text him saying "I miss you."
• He'll tell you you're beautiful...And he'll mean it.
• He will rack up a huge international call phone bill just to hear your voice.

Most importantly...

He will wait for you no matter what happens.

Keep in mind...these are all personal experiences and may be different for you and your guy, but this is how it was for me.

Good luck :)