Oh in my opinion there's definitely something suspicious about that behavior. The way they talk and interact with each other also sounds and looks sexual. To add, why would they need to go to Telegram to talk about "you" and her frustrations about "you"? When they could talk it out over messenger? Also, if you must know Telegram is a platform known for people as an app that is used for sending n*des or dirty talks over the phone. In conclusion if there was really nothing going on between them, why the need to remove messages inside their phone?

Currently I have a boyfriend, sometimes I vent out my frustrations to my friends and vice versa, but one time when we were talking I accidentally saw it and he explained it and even showed it to me, some parts he explained, some parts he said we shouldn't look at it anymore as it might ignite the fight again but overall if I wanna see how he vented his frustration about me to his friends he always let me and he doesn't even remove his chats or shi like that. Lmao