I really love someone and he says he does to but i dont belive him ?

I'm 12 please read on I need help . Thers this guy in my class about. 2 weeks ago I told him tht I love him I really do he said He does and on the day after he Didn't say a thing he was actig really diffrent . He said he likt me for a long time amd he used to lyk other girls too . The thing I'm worried bout is were not going out but he texts me sayng tht he loves me . I'm worried he dosent show it at school help!!!!