I agree a lot with Ladyone. The mother/daughter relationship can be really difficult for both. There are a lot of emotions and expectations, and if you don't honestly like you are treated by the other or how the other person lives their lives or behaves, it's not just irritation over those things, but the disappointment that you don't have a mother or daughter who fits your expectations.
If your daughter has a young family, she needs to find the kind of wife and mother she wants to be, and it may be that your example is so strong - and not exactly how she wants to do it - that in order to find her path, she needs to have some distance from you at this point in her life. There could be a lot of things though.
You suggesting that she's jealouse and wants you to be needy doesn't sound very mature on your part. I seriously doubt that's what she wants. I think you need a reality check on those judgements, which are your way of feeding into this problem.
I suggest you really think back to what she's said to you about the situation over the years. Has she told you that you're too critical, or too controlling? Do you try a bit too much to be "helpful" by making unwelcome suggestions? Many mothers of adult daughters do these things and don't see how intensely irritating it can be to the daughter!
Also you say you think she's jealous of you being "happy". That's kind of a weird statement. I am guessing you've made a change in your life to "be happy" such as finding a new husband, perhaps one she doesn't like or doesn't approve of? Or have you made some other decision to "be happy" that has had negative consequences for your daughter or other family members?
I think you are not being honest with yourself -you have a part in this, and I seriously doubt that any daughter wants her mother needy, ill and unhappy. And you casting that judgement on her is probably an example of part of the problem... giving her motivations that suit you instead of honestly hearing what she's telling you.
