First of all, it's very possible for a straight guy to LOVE another man, but not to be IN love with him.
Second: are you asking this for your friend or for yourself? There is nothing wrong at all with two guys being best friends who are intimately close, and I don't mean in a sexual way. Two buddies who love each other and aren't afraid of saying so is a concept that's come a LONG way. And because some people still think that only gay men are the guys not afraid to show their emotions, there's still a long way to go.
Having a friend who loves you, cares for you, would lay down his life for you - that's true friendship, and you should cherish that with all your heart. That is something some people will never have in their lifetimes, and even worse - you may not have it with the person who's SUPPOSED to feel that way about you, whether you are married to them or not.
So unless the friend is telling you he loves you as he's ripping your clothes off and you're falling into bed together, then NO, it's not "gay."