We people once want to fall in love even if it does not last forever still we want to experience it because then only we can understand the real adventure and ups and downs that come along the love.
You never know when will start to feel for the person and loves to come out to be with the most unexpected person because "love is not a theory, nor a subject that you can ever learn or understand".
Robbert knew very well that he was hurting her and eventually he will leave her when the time comes but still his heart wanted, what it wanted. There are different types of love, and in the case of Robbert his love was selfish, and he only wanted what he desired without caring a bit for the other person.
Cath was severely depressed now one part of her wanted to ask him why he did that to her and another part still hoped that he would come clean. That's how love is, it never fails to find excuses for the person we love even if they are strictly wrong. Sometimes even after knowing about their lies we people tend to cover their facade for the sake of love that we are holding, we start to fear to lose them and our dependency makes them arrogant. They start thinking that the other person will never leave and take them for granted but as we know even Gods have their limits and we are mere humans.