If you want to buy physical volumes June manga, Sublime, and even Tokyopop sell them. For just buying digital chapters Renta is your best bet.
renta website, amazon website, ebay website, as well as these two websites (but I don't remember if they sell it in only english or both english and japanese):
https://junemanga.com/
https://www.sublimemanga.com/
I hope this helps!
Renta has digital copies which you can purchase for a limited time. Some can be bought for an unlimited time as well. They have quite a number of good BL there.
You can also buy physical copies here. https://www.rightstufanime.com/
Where can I buy english manga online? Specially BL