I need understanding on when it is ok for a support to roam

I got stuck with a thresh support who managed to help secure 2 kills early in lane so we had a slight edge and if we kept up the pressure we could of taken 1st turret very quickly or simply just make the enemy bot 100% useless. However when we hit lv 4 he left lane to gank mid. I didn't really mind but then after his fail gank mid he goes top and tries there and camps in the river brush. When thresh failed his mid gank the enemy bot immediately started to zone me out of exp and cs as they should. After the fail gank top he recalls and goes mid again and blew a flash this time.

He comes back to lane only to have our turret already at 25% and me being underfarmed from the harrass i was taking and bam the enemy bot lane is back in the game. So with thresh back in lane I return to buy and heal but he goes mid again and then the enemy bot takes our turret...

IDK man IDK I feel like this guy was absolutely retarded but his argument was that he wants to snowball all the lanes which he failed to do and that him roaming wasnt the reason I lost lane that I should of been able to 1v2 cause i got 2 kills.

Is it really ok for the support to just randomly take off like that??? I mean if its ok Ill just take it with a grain of salt next time it happens...