I did meet the guy in my work place. He came over and see me. He asked my phone number then he text me the days after. At that time, I didn't interested in him, we just talked sometimes on Facebook shortly. After 2 months, he asked me to have lunch then we were going for lunch. After seeing him, I am very interested in him. We text more often and he asked me having lunch with him lot of time then. I feel very happy in that time, it was around 10 days. We did text everyday. He said that he like me, and I also told him I like him too. He is very busy with his job. He work everyday from early in the morning until late. I was thinking that he like me only and he was interested in me. He was care about me too much. But sometimes when I text him, he didn't reply. Yesterday, I came over his workplace to help him do something and also there is other girl came over to help him as well. Then he did care about this girl much and he didn't care about me anymore. I saw he and that girl flirt each other, they look very happy and like each other. So I don't know that did he play game with me? Is he interested in that girl or me? What should I do now? When job finished he asked to drop me home but I said I can go myself, because I know he will also drop that girl home. I don't want to be third person. Then he didn't text me until today. My feeling is very bad now. I am so confuse what he is thinking about me and what we are going to meant?

So he was talking and texting. And he said he liked you. And you came over to ( somewhere) obviously without calling ahead.

You have no right to expect him not to have another or even 2 or 3 other girl friends, he made no promises, no commitment. It is acceptable to date several people for a while till you get serious for one.

I know that he didn't made any promises or anything else. I cannot expect form him too much. So should I give up now and let him with other girl. I think he did know that girl longer than he know me. I am very interested in him. But I don't know what should I do to make him is only for me. :(

I actually experienced this before. He will probably ignore you and then he will forget about the other girl and start talking to you again.
But since this happened to me my relationship isn't as strong as it used to be.