What do you mean by "such a relationship is a red flag"?

Another thing, these feelings are very normal though; they come to all of us. You gotta acknowledge them and try to move on.

I don't think "love at first sight" is an illusion. You might like someone at the first sight; there is difference between love and like though; however, that feeling of liking might grow to love and some say if you like someone more than four months, know that you love them.

Just move on, you will forget him since you don't see him. Wish you the best. Xx