Help! Who can tell me why did I fail to do Tiramisu?

Originally said that I would send a Tiramisu recipe today, but I failed yesterday.

I don't kmow why, I feel all the steps are correct. But the problem was when I mixed the stiff peak mascarpone cheese and stiff peak egg white, the texture became watery!! just like:

So，who know where the problem is? I didn't add any water.

Buuuuuuuuuut! We haven't waste the failed food, we put it in the freezer, and finally it became a Tiramisu ice cream!! As delicious as Tiramisu cake!