How can you show your gratitude and deep love to her if you cant ever see her?

It depends. Are you not able to see her because of work/school schedule? If so, make sure that the time that you do spend with her is all quality time. Skip going to movies because there is no room for conversation. Instead try packing a picnic. Take her to the beach & tell her how you feel. If it is a long distance relationship, then perhaps stay commited to the whole communicating regularly thing. Do emails, phone calls & do something unorthodox now days. Write her a letter or send her a card through the mail. Just be creative, spontaneous & most of all thoughtful and honest. It goes a long ways.