I feel very sorry for you OP.
Grief like his is shocking, he's like a sinking boat in a storm.
He grabbed out at the nearest anchor to try and provide himself with a bit of familiarity, distraction and comfort after barely 12 weeks.
He is a deeply confused man.
Grief can make you very very selfish as you fight to survive the overwhelming pain of loss.
He undoubtedly love bombed you as a distraction.
He's still in year 1 of his grief.
Year 2 is invariably a far greater shit show of emotions, confusion and disbelief at the reality of his loss.
There is no going around grief, the only way is through it.
With you he was trying to go around it.
Who can blame someone until you are in their shoes.
But YOU are collateral damage in this, even though you desperately don't want to face it.
He is keeping everything separate because in his gut he knows this is avoidance on his part rather than a real connection.
That doesn't mean he doesn't like and care for you, but he is in the fog of grief and for a long long time will take one step forward and two back.
The very wisest thing you could do is take gentle kind control of this situation and remove his choice in the matter.
Stop seeing him and go completely cold turkey.
If it is meant to be, it will happen.
I think you could waste a lot of time in this situation and be no further than you are.
He may always associate you and his emotions to the immediate aftermath of his grief.
Eventually he will likely want to heal and move on naturally and your association will be a reminder of that pain.
Your best bet is to accept this is the wrong time and end things and take the high positive ground and allow him to heal.
His reducing your contact time is indicative of him realising things are probably not right.
I appreciate this is deeply painful, but wishing things were different simply changes nothing.
Grief takes time and he clearly needs it.
Don't be used any longer by him, however kindly.
Move on, time to protect and put yourself first.
Wishing you well.