<human>: Can you succinctly summarize the text in 1-3 sentences?

Hello reddit.... I need advice, I don't know what to do.

So... I've known this girl for about a year and a half; we started talking, were friends for quite some time, then earlier this year we dated for a bit but that didn't go so well, so everyone just carried on with their lives. 

Then, about 2 months ago we met again and had a good time together, so we decided we should try it again. We dated for about a month and everything was good, and we decided to make it an exclusive relationship; we kept seeing each other, talking frequently, you know, normal relationship stuff. Then a few weeks ago she started to treat me kind of indifferently, our talks were extremely and progressively neuter, last time we saw each other was extremely distant and we don't talk to each other since about a week ago.

I don't understand why she started pulling away suddenly, we had this honesty agreement that if one wanted to end the relationship or just wasn't sure, we could end it and everything would be fine; also, I've tried talking to her to see if everything is ok on her end (she has family problems, divorced parents, etc) and she says everything is fine. So I don't know if something's happening to her or what the fuck is going on.

What bothers me the most is that it's as if she's a completely different person now... She seems less happy with life in general, she used to be a really cool, fun and sweet girl and overnight she became this boring, cold, sad person. She has never been like this during the whole time I've met her; she even talks and writes differently. I swear I've done nothing to cause this, so it must be an external factor.

What do I do?? Should I try talking to her again? Break up with her? Wait until she puts her life back together? HELP!
<bot>: Been in a relationship for a few months with a girl I've known for about 2 years, everything started great, but now we don't even talk to each other.