The person who appears to be with you is notalways the same. Sometimes the person in your mind and heart are different. Never consider someone as your love on basis of his/her physical appearance . The person who looks beautiful is not always the same from the heart. signs of a person really interested in you:
One who loves to look into your eyes ( the person who took off eyes after watching sometime is always a cheater)
One who is always shy before you(not all the persons)
The person who is afraid of changing looks (because he/she don't want to look different before you)
And the last and most important point is that if a person loved someone or was in relationship with someone (seriously) can't be yours.
Consider these points and think if I am wrong .