Please post in English next time. ^^
Well, yours is more like an online relationship rather than a long-distance relationship mainly because you two haven't even met yet. And it's harder. It seems to me that he's just in the mood to be your boyfriend whenever it's convenient for him.
I'm in a long-distance relationship and sometimes, my boyfriend can be "cold" to as well, (at least, cold enough considering he's always super sweet) but that's because he's preoccupied. At first, I thought, "[b]WTF[/b]. You can't be sweet just because you're busy? Does it take [i]that[/i] much effort?!" But I eventually accepted it because guys really couldn't multitask. >.<
Wait -- when you said "namatay yung ka-MU ko," you mean literally dead or his/your feelings died?
I don't want to assume or anything, but it looks like your boyfriend is trying to break up with you by giving you the cold shoulder. Even though your relationship is online, a guy wouldn't ignore a girl for a week just because he's "busy." He can't even send you a message? Also, from his response, he's probably beginning to lose interest. Seriously. He wouldn't say, "Gusto ko eh." if he truly cares for you.
And to answer your question, no, it's not an acceptable excuse for him not to text you just because he's busy. He could at least text once a day, but he doesn't do it. :\ I think you should confront him. Tell him you want to talk. If he says he's busy, then tell him it's about your relationship and how he's been acting lately. Ask him if he still wants to be in the relationship. Better confront him now than regret it later. [b]Demand an answer.[/b] Or at least an explanation. ~_~ If he still won't talk to you, then you shouldn't be sticking around anymore. You deserve somebody else.