Hello, thank you for choosing JustAnswer. My name is XXXXX XXXXX I hope to help you today.
I am so sorry for the difficulty you are experiencing in your relationship. Such problems are always very stressful.
From what you are telling me, it sounds like your concerns may indeed have credibility. It is dishonest for her to delete texts for the sole purpose that you do not see them. Because of this incident, your girlfriend should acknowledge that what she did was wrong, and that you have reason to distrust her. Therefore, assuming that she wants to make the relationship work, she should be more than happy to do what she can to make you feel secure in your relationship.
One of the main purposes of a relationship is to experience a special kind of joy. It would be self-respectful to take a break from this relationship for two weeks and reevaluate, if you are not happy within it.
I would love to hear how this works out for you. Please do not hestitate to e-mail me at firstname.lastname@example.org Good luck, and take care.