WHy is my girlfriend of 8 years not allowing me to use her phone when she uses my pho

Let's not jump to conclusions just yet. Confront her and ask her why she won't let you. Explain why it's unfair that she's allowed to use yours but you're not allowed to use hers. If she still won't let you, make it clear to her that she can't use yours either.

Chances are that she is cheating on him. Why else would she hide her phone from someone she claims to love and is supposedly meant to share intimate moments with?

It's possible, but its not good to jump to conclusions without actual evidence. If he's super worried about it, he should confront her. Then again, I'm no expert in this field so the advice I've given may not be the best.

He should confront her about no letting him use it and if she gets defensive he should tell her that she is making him think that she is cheating on him.

Why don't you ask her? And just because you do something doesn't mean she has to. Lots of guys do anal with their gf but in most cases it's not a 2-way street.

Don't automatically assume that she must be having sex with someone else.
Plenty of other reasons to explain why she won't share her phone.

Is she very stingy?
Unwilling to pay for things or buy people gifts?
It could be that she uses your phone to make free calls and save herself money.
But won't allow you the same opportunity to use any of her package minutes or spend her airtime credit.

The question should be why does an 8 year old have a phone

use my phone whenever she wants? Is this because she is cheating on me? How do I confront this and make her understand that relationship is a 2 way street?

Don't automatically assume that she must be having sex with someone else.
Plenty of other reasons to explain why she won't share her phone.

Is she very stingy?
Unwilling to pay for things or buy people gifts?
It could be that she uses your phone to make free calls and save herself money.
But won't allow you the same opportunity to use any of her package minutes or spend her airtime credit.

His girlfriend is not an 8 year old. She has been his girlfriend for 8 years.

woooosh

If he wants to do that he can

Bit of a jump.
Just dont let her use your phone. You can point out you think its strange behaviour, but some people are private.

That’s what he should do.