Should i ask for help?

So ive been dating my boyfriend for 3 months now, freshly together. We have been spending a lot of time together and everything seems to be going great, he is understanding, loving and patient.

He knows about my past struggles with depression and self harm, and he has been nothing but supportive and careful when asking questions.

Recently my mental health has been going downhill which is not unusual for me, but i recognise my bad patterns. I am scared to tell him that i need his support. I know it’s a lot to deal with a partner who is struggling, and i don’t want to put that burden on him, but i cant hide it any longer.

He has noticed my behaviour has changed and he thinks that he did something wrong, sadly after many attempts he can still tell that something is wrong.

I don’t want to scare him away, or bother him with my problems since we just started dating. Is it a lot for a new relationship? Any recommendations? Thank you a lot!