Question: how do you know if a guy has lost interest?
Answer: He's making excuses. In the beginning, he was all about you—when you called he ran. ... 
He's not as responsive on this phone. ... 
He's become defensive and rude. ... 
He stops asking questions. ... 
He's more vague and indecisive. ... 
There's no sex. ... 
You're only having sex. ... 
The relationship is stagnate.