Erection issues

B
He's 27 I will be 25 next month. When we start to BD he can't get it up all the way or can't always keep it up when we go to do the deed. This doesn't always happen but is happening more often, and I feel is taking it toll on both of us. Something's I feel he's not into me like he use to be, we have been together for 8 years. Like maybe he's bored with me, but he doesn't act like that's it, he always saying sorry when this happens and feels bad thou, and I tell him maybe we need to go to the doc and make sure everything is ok. We want a baby but aren't trying really hard to have one right now. What's going on with him, I think he's upset with himself about this and its causing us to fight, ne advice is needed and helpful plz and thanks!