First - you say you've tried everything to no avail and so I am assuming this means proposing as well. If that is the case, then how about this non-original thought: "If you cannot be near the one you love, then love the one you are near". So, are they any others nearby?

Second - you can't make someone feel the way they don't want to or are unable to feel. That is too much responsbility to place on another person. You are responsible for your own happiness. If your happiness includes occasional time with your lady, then enjoy that for all it's worth without worrying about what more there could be. Love is like ice cream. . . . enjoy it now! Don't worry about whether you'll ever have another dish.