1- This type of behavior isn't really normal for a man, for a female yes at times but for most men no. Most would say that when he is ignoring you it means that he's off doing something he isn't supposed to be doing. If you have gone an entire day without a text message from him and you know he's not at work, or he doesn't text you back hours after you have text him...I'm sorry but there is a good chance that he is doing something he shouldn't be doing. However if you have text him and he doesn't respond as fast as you expect him to, calm down he might be choosing his words wisely as to not cause an argument between the two of you
2- a relationship without communication is like a car without gas....you can start it all you want but your not going anywhere. This goes for non-communication in a relationship, you can be in a relationship but without communication it's pointless. If you do not talk to one another about issues that you have the relationship will just be at a stand still. Just because you might be telling him what he doesn't want to hear, doesn't mean it shouldn't be said. It needs to be bought out into the open. You as his girlfriend need to be able to say anything to him without fear of him getting upset. You need to let him know that you entered this relationship as partners and it should still be that way. A relationship needs communication, talk to one another because no one deserves to feel ignored. Sit him down and let him know that there are some issues weighing heavily on you and you need to get them off your chest, him being your partner should understand and want to sit down and work out these issues. However when you sit him down do not start yelling at him and telling him what you "think" he is doing because that will do nothing but cause an argument...tell him how you feel in a tone that will allow him to listen and not mentally mute you.
"If someone truly loves you, then they shouldn't make you feel like you have to constantly fight for their attention"