What is it called and what kinda people is this?

When the person comes into your life humble and accepting and attached to you,wanna be up under you 24/7 and have nothing going on in their really and plays along with you.then one day they get a job and weeks go by and now they become more distance towards you rarely acknowledge s you among people and forgets to text you sometimes calls you anymore get snappy at you easlie things that meant a lot to them seems to not matter barely anymore .the more there life progresses into something more meaningful the more they seem to forget about but pay other people more attention and become flaky othen.becoming more secretive .phone hangs up that dont even try to call back nor explain.when all you have been is a great person to them and there for them,thick n thin .whats that?