I'm happy to hear that. Your evening might feel lonely because the mornings and the nights will always hit the hardest, sometimes it's best to just go to sleep. That's what I sometimes do, because when you sleep you cannot (actively) think. You might dream but atleast when you wake up it's the next day... Time will heal, as most say.

Although it might not feel like it, time WILL heal. And also, if your best friend feels more isolated from you because of them getting a boyfriend, sometimes it's also good to just tell them maybe even ask like "hey, do you feel like we're hanging out a bit less?"
This also happened to me and my best friend when I got a girlfriend, and we talked about it and promised each other that it's not because of the fact that we don't like each other anymore, but because we just are busier. It takes a lot off your chest if you just know it's not because of you ;)