<human>: Can you condense the text into a few key points?

me (22) and my boyfriend (21) have been dating a little over 2 and a half years. 

My entire life I have been underweight, and not by choice. I'm tall, legthy, awkward and bone skinny, and it seems no matter how hard I tred, I couldn't gain weight. I've accepted this as my body type, although I would very much like to gain weight. I've gone on crazy weight gain diets, like eat fast food twice a day, eat as much sugar and carbs as humanly possible, protien shakes diets; nothing really works. When I started dating my boyfriend it eventually came out that he wished I would gain weight because he likes girls with curves... I continued trying to gain weight, but with no success. As the years have gone by he has been getting more and more upset with me that im not gaining weight. 

Recently we started talking about marriage. My boyfriend told me that he would propose to me once I gained 30 pounds. If I couldn't gain the weight he would not propose.  He says he wants me to be healthy, active and strong and I can't be any of that when I'm so thin and frail, which I agree with. I have explained to him over and over that he needs to love me the way I am, and he insists he does but then situations like this arise. Is this a normal request for a man to ask a woman to do before he agrees to marry her? Is it any different from telling an over weight person you wont marry them unless they lose weight? How should I handle this situation?
<bot>: Although I've been trying my entire life to gain weight, my bf told me he wont propose to me unless I gain 30 pounds.