TTC But husband doesn't always cum

Hi, I'm now to Glow, first post on here.
My husband and I have been TTC for 8 months, and I just started to track ovulation last 2 months.
My husband and I have regular sex, especially during fertility window, however he doesn't always ejaculate. Sometimes we can go 3/4 times with nothing. I know it's not his fault but each time there's nothing it breaks my heart that there another chance gone. Has anyone else had anything like this? 
Thanks