Advice ! whats up with him.. and what shud I do.. ?

Oka so I met this dude about a month or so ago and i really like him. One day, we just pming each other & said we loved each other and everything was fine. He loved me more than a friend but i just loved him like a best friend or brother but i really liked him more than a friend. So..the days go on and for about 2 days, havent talked to him but then like the next day, we were talking and he said lets just be friends.. Right there i just felt like so depressed. I was a little confused..becuz i didnt noe what he meant at 1st and so he explained it to me and i was like Oh..He also told me he didnt like me anymore.. but he liked this other girl idk. and we havent really been talking much anymore.. In just like 2 days he changed his feelings about me. So my question is: Should I just get over this guy or should I keep trying? and why do u think he suddenly changed his feelings about me?.. thanks..