All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
As long as the picture that the person sent does not include anything prohibited, he bears no sin for choosing those whom he wishes to send it to. This does not involve taking girls or disbelievers as friends. However, the person should carefully choose the material that he sends on such websites and apps and make sure that they are good and Shariah-approved. It is even better if he sent material that calls to Allah, underlines the manifestations of His omnipotence in the universe, and the like (of good and rewardable purposes).
You should also fight the obsessive doubts which you seem to be suffering from, as getting carried away with them leads to grave evils.
Allah knows best.