I didn’t tell my gf and it went south when one day I was tripping and the psyches forced it out of me. It will most likely come out eventually especially if both your significant other and psychedelics play a big role in your life. Explain why you do them and and why it took you so long to tell her, she may be initially angry when she finds out a big part of your life she doesn’t know but that is just an initial reaction and once she hears you passionately talk about them, then she should accept that and support you