If I’m reading that last one correctly… your phone was in the car but she said you didn’t need your phone because she wasn’t on her phone, then her phone dinged with a text message and you questioned her about it, right?

It’s entirely possible, though, that she WASN’T texting but someone just randomly sent her a message. Happens to me all the time because I rarely text people first unless I have a question or something. So maybe it would help if you could start thinking of scenarios that give her the benefit of the doubt instead of asking questions about it right away?