Boyfriend on Zoloft

My boyfriend is on zoloft and it’s hard for him to cum and his sex drive has decreased. He is able to cum when I blow him but when we have sex he isn’t able to cum. I feel so embarrassed by this and even tho he tells me it’s not me I still get really upset by it. He isn’t supposed to be coming off of Zoloft anytime soon so this most likely won’t be resolved soon. Anyone been through anything similar or any advice?