I agree, for the past chapters he has been really selfish of Roselia’s love since he hates the fact that Roselia loves Ain more.
Not anymore. He try his best to love & live like normal family. He just feel left when Roselia always focused to Ein when they re three In one space. If Roselia can balance her attention maybe he will not feel be left there. But the style now is changing due to his high patient. U guys need give credit to him actually. Roselia is not clever to give the explaination but Claude be rational & not focused just one aspect do the rest. Actually, Ein still listen to his father most when his feeling is at climax. Roselia is a person to comfort him but who re always be there solve his conflict still his father.
Eh I’m still not convinced yet but my opinion might change thru out the story
I'd say that the fact that he's trying to convince his son that having a younger sibling isn't all that bad instead saying "I'm giving you a sibling whether you like it or not" shows that he is moving in the right direction. Plus he still has to convince Roselia to have a kid which I feel is going to be a trek so he has plenty of time to build up his relationship with his son.
... like I don't want another kid in the picture until that dad sorts himself out and fixed his relationship. Like if you can't even love your own child what makes you think you can make another.