My ENTP friend just broke up with his girlfriend today... and all we've ever done was tease each other/banter, so I don't really know how to be "serious" with him in a useful way. I told him I was there if he needed to talk and he said "Thanks a lot". Didn't wanna answer cause it seemed kind of useless to the conversation.. he probably wants to be left alone until he feels a bit better.
You did all you can.
ENTP may be likely to appreciate that you offered your concern and support and your openness with him will let him know that if he needs to talk about it, he can. You've done your part. The ball is in his court now.