How long does it take for this nre to wear off and she returrns to nornal again?
Because they are long distance, the thrill of being in a new relationship can be very durable. It has been my experience that new relationship energy is something that comes with most sexual associations, and is only calmed down when enough "reality" time is spent with someone for the rose tinted glasses to come off. When a relationship is allowed to exist without this overload of reality to dull the excitement... that shit can really drag out.
As far as her getting back to "normal again", you may need to start adjusting your expectations on that particular mark. Normal is just an expression of the way things have been in recent history. However, when things change significantly or for a long enough period of time... that is the new normal. There is no guarantee that the relationship you have with this person will snap back to a previous save point.
With any luck your relationship will reach a new point of flourishing, but that isn't something that is destined to happen.
whay can I do to advocate for more of her time.
Advocating for something just means speaking up and making your desires known, it doesn't mean that you get it. So in this instance, asking her on a date (whatever that looks like for the two of you) would be an example of advocating for some of her time. Keep in mind that she may not be into it, and may prefer to spend her free time chatting with her new friend.
I suggest using an approach that is inviting (as opposed to work, or extortion), and being a good receiver regardless of what response you get.
When she talks to him shes sweet and soft, giggling, smiling non stop, she never ever does that with me and its driving me crazy, is it normal and how do I deal with it?
It's normal to be jealous, envious, and insecure... yes. It isn't something that I recommend leaning on as a healthy way to live your life, but it's certainly a normal hazard that we all encounter here and there.
I recommend stepping away from concepts like "she treats him one way, but treats me another, and it's not fair". She is treating him the way she is, because that is her association with him. She treats you the way she does, because that's her association with you. These two things aren't supposed to look alike, and they most likely won't.
Instead, focus on what it is about your association with her that you do like. Do you like things about your association with her? Do you guys have interests in common and things you enjoy talking about? Are there activities that you both enjoy doing together?