That scene in the bar was just awash in sexual tension. Wow. Uncomfortable to watch, but if you are not as repressed (regardless of sexual orientation) as Gus, it can be a thrilling feeling to connect with someone, and have that energy basically coming out of your pores. It's such a well made show, classy and brilliantly acted, and produced. The details really add to the overall product.
if you didn't get that scene, (again regardless of sexual preference) I'll put some thoughts down about it, the scene is about connection and vulnerability and that place where you can lose yourself in (sex, flirtation, intimacy, attraction), it's that moment where you connect with someone, and an instant turns into an hour of conversation, and sometimes sex.
To go deeper, Gus lives a compartmentalized life, he's a gangster. He can't speak poetically of wine and travel with his guys, or his workers, or his bosses. He just can't. So he has other outlets. That night, and I have been there, he wants to lose that part of himself, the guns and killing and tension, and just be that other person (which for him is also the fact he's gay, but that doesn't even matter THAT much here) the person who likes wine and traveling, and romance, to put it bluntly.
You ever been stressed like that, when you want to disappear into those parts of yourself? And Gus is too repressed, too in control, to afraid of that vulnerability to go there. He will go up to the line and not cross it. He wanted that guy to come home with him that night, and he would have. He doesn't have to be Gustavo, he can be a different part of himself.
it's not the first scene like that, but it's a very well done version of a timeless kind of tortured hero theme.
And Mike did a similar thing to cope, he broke character, and broke ranks, and made himself vulnerable (in a sense to ask forgiveness) to help him forget that part of himself, that murdered a young man whom he admired. That life takes a lot out of people.