Where’s the Finish Line?!?

Hope

My bf and I have been together for 2 years and officially living together for 8 months. For the past 6 months we have been having some issues in the bedroom. We don’t have sex as often as we use to, he doesn’t stay hard as long, get as hard as he use to, and he RARELY finishes. He always makes sure I get mine but he knows I want to have a child sooner than later which was discussed and agreed on a long time ago. I’m just not sure what the problem is. Before we moved into this house we would have sex at least 4 times a week and he would finish about 50-75% of the time and I would stay with him at least 5 days a week at his place. I’m at a loss for what to do. And honestly I’m losing hope for our future.