My boyfriend doesn't reply when he sends a text message on business trip.

In this case, I will give you a definite answer. He doesn't love you as much as before. He is tired of you. It may be hard for you to accept at the moment, but he is telling the truth.

He is too close to you, so you need to distance yourself. For example, if he doesn't contact you for a while, don't contact him either, which shows that you are dispensable to him.

He didn't reply to your message all day. If he is really busy at work, socializing or meeting, he should understand, but he is busy and should give you an explanation instead of not returning messages. It is estimated that 90% are dating other girls, and he will be annoyed by your news and phone calls.