Can you still have a loving relationship between MC and Anne in the end, even if you're on the cheating path?
That will be up to the Dev. I don't see it happening, but he may write it that way. For example, if the MC is on the cheating path and Anne is with Martin (MC's father-in-law), Anne will blow up on the MC (after the Mia scene, if I remember correctly) and demand that he become truthful in what he's doing (no more cheating for the MC and the "Faithful" switch reverts to "True"). Yet, the very next day she is cheating with his dad again and the script plainly states that the MC doesn't know it and she's not going to tell him. At some point the MC will find out, then what?
Again, the Dev can write it whichever way he chooses, but in the real universe their relationship is pretty much on the rocks unless they go completely 'open' and do whatever they want with whomever they want whenever they want.
Further complicating matters is a few script errors that exist which break immersion. If he is not cheating he will be accused of it and admit to it even though he's never been with anyone else. I wish those little things would be rectified at some point. Regardless, we're just along for the ride and let's see what happens.