C++'s 'friend' like solution in c#?

Question

HI!

My problem is:

I have 2 classes. A Form class called MainForm and GamePlayManager class. 

MainForm handles graphics and GamePlayManager handles the logic beyond graphics.

I separeted them into 2 classes because I don't want to mingle them into one (I think it would be a nasty solution).

question:

How should I implement them, to access the classes of each other?

I think public, and internal modifiers would be nasty solution. Setter and getter would be too elaborate.

In c++ there is friend modifier, however there is no friend in c#. 

What is the solution for my problem?

thanks, in advance

Martin