I had the same situation. I was in love with a man, who would not and did not want to love me. But I was honest with him, and didn't give up. As long as you are strong enoug and don't become psychotic there's nothing wrong with doing what you can to SHOW someone you love thim in hopes they will love you in return. But from my mistakes let me offer some advice. Be honest. Always. Be prepared to get hurt. (So make sure she's worth it) Be prepared to fight dirty if possible. And last, be ready to always question yourself. My boyfriend really loves me, matter of fact we're getting married in Sept., but I wonder sometimes if it will work because I "forced" him to love me. But he tells me he's glad I did or he would have missed something great.
Just show her your heart, open up to her but don't smother her. In my opinion flowers are so done. Don't do it. If you do, don't do roses. Be creative. The best gift I gave my boyfriend, I learned how to cook his food from his native country. That's when he said he fell in love with me.
But, if she doesn't RESPECT the fact that you love her so much, then she's not worth it. You can give your whole heart to someone and still go on if they're gone. If you don't you will miss out on so much in life, and if they leave, you pick yourself up, and try to remember that there must be someone or something so much better out there. Without love, life is only half lived. Good luck!!