How can you determine if your partner is an alcoholic

I 56 F have been with my boyfriend 55 M for 8 years. We have lived together for 7 years. The last two years whenever we go to hang out with friends, concerts or anywhere they sell or have alcohol, I will have a couple drinks but he has to drink until he his hammered. The last few times he doesn’t remember the end of the night. We don’t drink at home unless company comes by and once he starts he has to continuously drink until he gets extremely drunk. I feel like a babysitter sometimes. We both have adopted children that we are both very close too. I feel like this time in my life it should be my best life and this does not feel like it. I have dealt with drug and alcohol abuse in my past. He is functioning, goes to work ever day, pays his bills, no abusive ect My relationship is suffering I am looking for an outside opinion?!