Every choice changes something and gets different images, there are 9 routes through the current game (If you're playing the 'Is this NTR' story). I'm not sure what you mean by follow a girl from a third phone?
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I mean there are probably more, that was just an estimation. If you make different choices you get different routes. Just make different choices each time and you will see different things. Some choices interact with each other too, so making both, or making one and not the other will get different results.