Boyfriend staying out late....

So for the past 4 months my bf of 14 years has been going out to a casino nearby. We have an 8 year old and a 3 year old. He sometimes waits until there asleep to go. But he stays out until 2, 3 sometimes 4 in the morning. I’m ok with him going once in a while but it’s now become 4 nights a week he goes. I know he is going to a casino because he gives me his winnings to deposit. He isn’t putting us into debt or anything. And At first I was ok with it because I know he is bored of being at home all the time because of COVID. And I enjoyed some alone time and peace and quite. But now it seems like he is ready to run out the door all the time. And I’m left to handle the kids and the night routine which doesn’t always go smoothly. How do I handle this? If I talk to him about it he isn’t one to express his feelings he will just say fine I won’t ever go again and then pout about it.