No, Guts and Casca are as real as love can be in Berserk which doesn't have much of it.
What they didn't show during that sex scene in this recent movie was Guts damn near strangling Casca to death because having sex with her made him remember when he was molested as a child.
When he opened up about all that they both fell in love.
I trust this since you got it directly from the manga. I personally had to stop reading when Guts was raped as a child, so I've based most of my opinions on the anime and now years later these movies. Its good to know they genuinely cared for one another.

Gambino
They were so close to making it.



breh you just finished knee deep in some crevy and you still thinkin about this nikka 
dude was aight with me until he whored himself to that dude for a bit of paper