Why doesn't Michael "tell the nice girl he loves her" while on the phone to Kay? He seems embarressed infront of the guys, but why? Most of the guys there were coupled up.

"Macho men" of that era weren't supposed to express "mushy" sentiments to women while in the company of other "macho men." Also, Michael may have been embarrassed to be showing himself pursuing his private love-life at a time when his father was near death--and all the other guys present who were "coupled up" were sacrificing their own private lives for wartime duty.

Michael wasnt really a "macho-man" that time around the movie.

Even if he wasn't a macho man, I'm sure in that company he wouldn't want to appear all loved up, especially considering all the things going on. Also, he was in the army, so I'm sure he's used to not being all sentimental in front of the 'guys'.

Pippi

The fact that he wasn't thought of as a "macho-man" is even more of a reason that he wouldn't say it.

Men usually behave that way. Possibly sugary when in their girls' company and definitely all-macho in front of their pairs. It's due to the way men are usually raised. Being loving and openly showing affection is considered a women thing. Things are changing now, but it's a long way.

I strongly believe that the only reason for it is Michael's independent character. He never was a man to give his feelings away, and of course he would think that his love for Kay is nobody's business. It's his privacy. Very much like him. Just notice the way he rolls his eyes when Clemenza starts joking about that!

I agree with Justme lol I was about to post the same thing too till I saw he had already said it

It's interesting that after Michael becomes Don, he tells Fredo, in front of Tom, Neri, Johnny Fontane, sundry bodyguards, etc., "Fredo, you're my older brother and I love you..."

I wonder if he had more confidence to say whatever he wanted now that he was boss (just let anyone try to laugh at the Don when he tells his brother he loves him ), or if it was more acceptable -- even customary in the mob life -- for the men to publicly express their love for one another more freely than they would publicly express it for a woman.

With the men, it seems that there is no shame -- in fact, there's even honour -- in publicly declaring love for a fellow mobster with whom they had a particularly close fraternal or paternal relationship. It's as if they feel the bond is more poignant because death could separate them at any time. I think of how Hyman Roth, with Busetta and Johnny Ola right there, tells Michael how much he loved Moe Green, since they had a metaphorical father-son relationship.

Interesting point, Cristina! But, Michael's expression of "love" for Fredo was, IMO, really cold and perfunctory--almost menacing, as if the "...but don't ever take sides against the family again" were a threat, which is what I believe it was. Roth, IMO, meant "love" more than Michael did, although we both noticed that he qualified it by saying, "As much as anyone, I loved him..."
My net: If either of those guys said that they loved me, I'd start shopping for a burial plot.

Indeed! Your comment reminds me of Michael's dialogue in GF2 after Kay announces she's taking the children and leaving: "You're my wife -- they're my children -- I love you -- and I won't allow it."

What a surprise that a nice "I love you" shouted in the middle of an argument didn't cause Kay to change her mind . It sounds like Michael could have substituted the word "own" for "love."

And earlier, when Michael is confiding to Tom after the Tahoe shooting, he says, "it's because I admire you and I love you that I kept things secret from you." Is he sincere? Or is he just manipulating Tom so Tom will gladly work more dilligently to stay in Michael's good graces?

I'm not saying that mafia members are not capable of loving their families. It's just an observation that in the case of young Michael and Kay talking on the phone, maybe Michael can't say "I love you" because he really does love her; but it's just too emotional and personal for him to say on the phone with all his dad's mafia cronies listening, ready to crack a joke. It seems that when "I love you" really means something else, it gets bandied about much more easily. Shame.