Can I send legal notice to my girlfriend for keeping me on hol for more than a year for marriage.

Me and my girlfriend are in relationship from past 3 years. We had promised each other for marriage. I am doing business for last 2 years and she is doing her job. A year ago I have told about her to my parents and they are ready for marriage, but her father told that time to wait for some months to settle my business. Now after running my business for 2 years and I am earning a good income from my business. But still her father is not convinced with my business and asking me to do job for fixed income which I don't want to do and also my girlfriend know about that on which she is ok, as she know I am always into business. It's been 1.5 year now and still me and my parents are kept on hold by her and her father for giving decision on marriage. Every time I ask her did she asked her father for marriage as our age is also reached 30, she ask for time from me to discuss this thing with her father. I love her and I want her so I always give her time to discuss with her parents and take decision. But now it's 1.5 year and still she needs more time and the topic has not yet crossed from the beginning. I want to let them know that I have waited a lot now and also gone through mental trauma due to which I lost focus from my business and also I am very stressed and depressed because of this waiting think. I want them to take the decision as soon as possible as I can wait more. But whenever I talk to her regarding this she always take more time and the result is nothing. So I wish to send a legal notice for wasting my time and keeping me and my parents on hold from last 1.5 year for marriage and want them to take quick decision regarding our marriage. I want to marry her and even she wants the same as told by her. But she is not able to convince her parents and her parents are just wasting our time not even giving us a proper decision, either they are ready for marriage or they are not.