Confused and discouraged

So my SO and I have been ttc for a year. we had a miscarriage last Christmas and have just not had any luck. So we have talked about more seriously trying and this week is my fertile week. we have had sex once and on my peak day he said he was too tired. It's so frustrating. He says he wants to have another baby ( we have a three year old already) but then doesn't want to have sex when we need too. I don't know what to think or feel.