Why is he still with her if he flirts with other girls?

I think he's both afraid of commitment and afraid of losing someone he does care about. You can't stay with someone for 10 years and not care about them, but I think he might be afraid that everything's going to change when they get married. Does that make any sense at all? That he thinks that being a married man will give him no more license to flirt, and from what you've said, it sounds like that's a big part of him.

On that subject, I don't think it means anything. I know a guy who was dumped by a girl because he flirted a lot (not cheating or ANYTHING like that, he was just kind of a flirt, but she took him back because he was devastated and she realized that that's part of who he was.

Also, the drinking? My dad does the same thing, and he's probably been doing that since he met his first wife (no commentary on her, seriously,) and he's probably as happy as a 69 year old man with a shaky business and oppositional defiant children can be (I mean that in all honestly.) You didn't mention whether he has to get drunk before going to bed, but it didn't sound like that was the case. Some people need to do that or other things before they can go to bed.

And you mentioned the thing where he usually complains about something she did? All guys can do that, and will. Two people can get along fine by themselves, but unless something good is really special, it won't be worth telling, will it? The bad stuff is more interesting anyway (Proof positive is the news.) So that's not unusual for a guy, and probably not even for a girl, though I don't talk to enough girls in relationships to know for sure.

Anyway, if you have to express your opinion, I would try not to be too accusatory of him, because he has fears that he's probably trying to overcome that you would just inflame. Be gentle, and, if you've taken my advice this far, I guess I could mention one more thing. Sound more curious, as if you don't fully know the situation, and he might even be more open, especially if there's something you're misunderstanding.

1) Maybe he's silently still feeling the waters, not sure if she's the one he wants to permanently settle down with. ~ would explain the flirting with other girls and getting her a ring to keep her quiet so stalling?(probably because of her over-bearing and dominant behavior?)

2) Has commitment issues, afraid if he settles down that he'll lose his indentity, especially getting pressure from her and he already has a feeling of this from her - might explain the drinking. But I will also add that 10 yrs IS a long time and usually guys if they are absoluetly sure if she was 'the one' - would have married her already long ago. So maybe just doesn't want to break her heart so hangs on and stalls but prolonging what needs to be done and is holding him back to begin with.

You should talk to him, see if he wants to talk- must someone to confide if he is drinking himself at nights which is not healthy and nobody deserves to be miserable. Be a good friend and lend him an ear.

I think part of the blame should be placed on her for letting him drag it out that long. 10 years together, engaged for 2 and still no official plans? That's just excessive.

It doesn't sound like he's happy and he's realizing now he can't "put it off" any longer. He's running out of time. They're probably comfortable in their home together so that adds to the complexity of what's going on. At that point you can't say "I want to breakup". You have to worry about splitting up the house, money or whatever else. It's like a divorce with few, if any legal ramifications.

I can't tell if you're friends with her, him or just an observer. I'm an honest person and if I felt comfortable enough with him I would just ask "What are you doing?!"