Stop caring about what other people think, it is your partner who is supposed to treat you right not third parties.

It is not up to you and/or your friend to decide if this is cheating. Only your and her partner can decide if this is cheating.

This would be the same as me saying "oh fucking another guy with no emotional connection is not cheating."

When you have a good time with your friends it happens that you won't check your phone, because you are socializing.

Also it isn't very polite to be on your phone ever hour to text someone else while you're a guest.

If you want you partner to send you a message when they are coming home then ask them "hey would you mind sending me a text when you are on your way home?" , But don't expect your partner to text with you all the time especially when they are visiting someone else.

You wouldn't like it if your partner was on their phone the whole time when they are with you to spend time with you?