How should i feel about losing money in Vegas when up previously?

I was previously up from 3 prior las vegas trips of $16,400 and I ended up losing $5,300 on my 4th trip this month. I was wandering if I should still be happy since I've won a lot before. I also wander if I should quit gambling since I get emotioanlly unstable and since I have new girlfriend since 2 months ago. I am 21 yrs old, I only play roulette game no slots, and I'm already a diamond player