husband won't ejaculate when trying for a baby

I've been taking fertility treatments to help me ovulate because I have pcos. We are also having timed intercourse according to my cycle dates. My husband will only sleep with me on the weekend or if I come on to him first. Durinf my ovulation days we had sex, but my husband couldn't ejaculate near the end of that time. It could be a medical issue. It has become very stressful and I'm beginning to think it's me or I'm not doing something right. I need help coping!