He used to act like he liked me but now he is sooo rude y?

he is my senior at work(only 1 year older than me)he is very nice and kind.....we used to joke around and he used to say i love you(whenever i did something good) and he also said to one of colleague that he is thinking of marrying me and when she said go ahead and he was like oo i think she is too young for me. He also tagged me a photo of him kissing a girl but then untagged it quickly(i dont if he did it deliberatly or by mistake)he also had it on his status that he loves me but its been 2 weeks he has started acting a bit mean towards me and if i say ooo i love you and he does not even say anything back i dont know whats wrong with him. Today he insulted me infront of my colleauge as well and then he started giving me big smiles and whenever i asked something he was like ooo did you just call me y?and then he rung me to tell that we have a meeting in the morning and started calling me love and babe??