My bf is sad and i don’t know what to do

So recently my boyfriend has been extremely unhappy bc of school and life in general i guess but he won’t talk to me about it! He stared seeing a therapist and i mean i guess it makes sense for him to talk to her bc she’s a trained professional or whatever but i wish he would tell me anything. I want to help but every time i ask what’s wrong he says nothing. The other night we were texting and he got so upset out of nowhere and said he didn’t wanna talk to anyone and when i asked what happened he ignored me. And rn i want to see him and this was our conversation. I don’t wanna annoy him by constantly asking what’s wrong but i don’t know how to cheer him up if i don’t even know why he’s so sad.