How To Know If A Boy Likes You

Why is he nice to me one day, but ignores me the next?

  perhaps he likes you yet feels he's coming on too strong some days then feels it's necessary to back off the next but over dues it. He does this not because he doesn't like you,but because he's insecure about liking you. The second theory is he might be bi-polar and my third is that he just has bad/good days and then these days determine his mood with you. I hope this helps  

There are many possibilities. You shouldn't feel sad about the situation. You don't know what the problem is.

He is just like that. Yes, he may be a person who is slow in opening up to new people. His nature is not that much extroverted. So, just do your thing, talk to him and work it out.Mood. Maybe his moods change due to some problem he is having. This is not about you in any way. There can be some family trouble or a personal problem. So, he is just a bit upset.He is not sure. He likes you, but he is not sure that you like him back or not. Even, it can be that he is not sure about himself. He is just thinking about the circumstance.

The best thing you can do now is go and talk. Talk with him. Talk bout anything-hobbies, movies and other fun stuff. Don't be insecure. Confidence is the key.

   Argh, boys!
He may be trying to play it cool, he may really like you...but he's just scared to show it, he doesn't want to get hurt and may be doesn't want to hurt you.
Maybe you need to be straight with him and just say that you can't stand this yoyo dating type thing, and he needs to get his act together, and if he doesn't he...well then you'll move on!
Good Luck :)  

This is really hard to say. You see: We only have the scant information that you've given and nobody can actually and truthfully say what goes through some guy's head that you've met a while ago. We're left to speculation -just like you.

Having said that, I can give you two advices:

Explore your reality with that guy: Find out what happened by contacting him and asking him directly. You might find out that there has been merely some kind of misunderstanding.

Do not ruminate too much about what other people might be thinking. Humans are VERY complex beings which have a lot going through their heads. You should be VERY wary of coming to fast conclusions. This reality is quite ambiguous and can have multiple ways of interpretation. Try your best and do not wait too long for somebody to tell you about something. Find out what's going on by yourself. You'll see: Your initiative will often pay out for you.

There are ways to find out a bit more what people are actually meaning if you're very observant and know a thing or two about body language. 

  So the short answer is that dudes often ignore you because it makes you go after them harder. There are, of course, other possibilities. I would wager that any guy ignoring you is thinking one of these four things:
1.) "Oh nooo, I am a shy goofball! What do I do with this girl now??"
2.) "I have decided that I am not into this girl after all. OOPS."
3.) "Okay, she's into me. Check. I can pick that particular plum whenever I want."
4.) "I am in high school and have literally no idea what I am ever doing. Where am I."