One thing a lot of women miss when trying to figure out if a guy has strong feelings for them is this one:

He will re-name you. Not necessarily a nickname or something playful, but a variation on your given name, or maybe a phrase to describe you.

Examples:

Natalia --> Nattie

Jane --> Janet

"little one"

Miss Phillips (not using your first name and playfully being formal)

etc.

But it has to be a name NO ONE ELSE uses--only he uses this with you. Men will do this subconsciously, and without thinking, and it expresses a sense that you are his "special friend", or you mean a lot to him. That his relationship with you is different from others.

(In Jane Eyre, the heroine realizes something has changed between her and Mr. Rochester when he calls her Janet and makes strong eye-contact for the first time).

Not all men do this obviously, but trust me, it is a sign. I find myself doing it with women I have affection for, without even thinking.