Is it cheating?

[QuirkyAzureSloth]

If a partner has hidden phone sex with her past lover, is it cheating?

Yes. Unless they have your permission, as is the landscape in some relationships, then no.

Yes.
Anything sex related with another person is cheating unless it is just watching and wanking to random porn.
Prostitutes? Cheating
Lapdance? Cheating
Sexting ex? Cheating
Having emotional affair with another woman? Cheating
The list goes on.

Of course it is

Yes of course it's cheating!
Unless you are in an open relationship.
Surely it's self evident so why do you need to ask?

How would you know unless you've been looking on their phone?

If it has got to the stage where there is such a lack of trust that you are snooping, then the relationship is a non-starter.

You know it is.

definitely a form of. I guess we've all had those chats that can go bit far though

All? I don't think so!

Don't assume everyone takes their relationships as lightly as you must do if you think sexting other people is a normal everyday occurance.

bit harsh

Fucking hell, way to turn it around on the op!

Talk about victim blaming...

If you mean she has phone sex with an ex whilst in a relationship with a new partner, yes of course it's cheating.

If you mean she has old phone sex messages via text on her phone which she keeps whilst in a new relationship, then no. Not really ideal though.

Do you mean your girlfriend has already cheated on you (with the 'lover') and has cheated again by texts?

No we haven’t ‘all’ cheated via sexting