Okay, I guess I am going to weigh in on this:
This is the pick-up side of the response and not the Doctor Phil show:
If you think she is losing interest in you, then one of the following scenarios is happening:
1. You are wrong you are just obsessing
2. You are right and there is nothing you can do about it.
3. You are right and there is something you can do about it.
First of all notice that the odds favor you not getting all distraught about this situation. Secondly, women generally lose interest in a man when she has complete control over him. So, trying to mollycoddle her is not the solution. The solution is always to be alpha. You need to confront her in a non-threatening manner. If it is a couple of small things or misunderstandings, you deal with them. If they are genuinely your fault, you deal with them and make a quick apology and move on. You don't supplicate, you don't obsess over them. If she wants you to change yourself, you politely decline and tell her, that you are your own person and that those are traits of your personality. If she can't deal with that, then you guys aren't meant for each other. Also realize, that the super romantic lovey-dovey relationship stuff doesn't ever last, it only happens for a small while. If that is what has left, then you and her need to set your expectations lower. Don't be possessive. If she isn't really feeling the relationship, tell her that maybe she needs to date other guys, and mean it. You should date other women. If you are completely non-possessive, there is a major chance that she will come back to you soon.