Object constancy?

I’ve had a long period of I guess what you’d call negative transference with my therapist, but it’s been gone for several weeks now, and that’s really nice. Last week was the first time in a long time that I left feeling close and comforted and it was just plain nice. I’m not sure why it’s different now. A few days later I was even a little freaked out that that good feeling remained. Yesterday the feeling started to fade, and I sent him an email which he says he welcomes, but won’t respond. But today, I woke up and it’s completely gone. I’ve tried to get it back by thinking about our session, but I feel nothing and that bums me out. I’m not sure if it’s because I’m back at work after having the weekend off and I have some stress related to regular work stuff. I know he’s still there and will be there at our usual time on Wednesday. I know he hasn’t forgotten me and I don’t worry about that. I just feel down about the fact that the positive feelings are gone. So much so that I almost feel like I’d rather not have the positive feelings at all if they are just going to vanish like that. What is this? How do I deal with this? Is this object constancy? I really don’t feel like I have this issue with other people in my adult life - just my therapist.