How do you know if a guy wants to end a relationship?

He calls you less and less. He doesn't want to hang out as much

Here are the BIG signs:
Making excuses
Making up small lies
Always having plans
Moody texts
Not replying to calls or texts
Excuses
Not telling you his feelings
Using short answers
Talking to other girls
No eye contact
Ignoring you or avoiding you
Always with friends
And the "we need to talk"
Hope this helps your situation:)

He doesn't call as much
doesn't ask about your life/your day
doesn't act interested in what you have to say (for example, you'd tell him something that happened to you and he says "sweet/cool/nice" etc.)
finds excuses not to talk to you-no service, busy, with friends, etc. Bc if he DID like you, he'd make time for you
you don't hang out as much
he doesn't initiate things (hanging out, phone calls, texts etc)
he doesn't tell you his feelings
he spends time with his friends instead of you
he acts detached, disinterested, and shut off
doesn't make eye contact.
hope this helps!