You can't tell if he is bluffing, you can get wrapped up in the belief that all EA's are out to get buyers or you can do what all buyers should really do and stick with the program. You have a budget, the max you were willing to bid was €250k that should remain the same for now. If you don't get this one or any others in the area for the 250k then your prices are out. Why not tell the EA that you have a max budget of 250k and will put that forward as your bid. If the other falls through he can come back to you. The higher bidder may pull out, or stall and you may be seen as the better option even though you have a lower bid.
Remember its not about who is right or wrong, it's just about you getting the house you want for the price you are happy to pay.
Remember its not about who is right or wrong, it's just about you getting the house you want for the price you are happy to pay.