I went to an engineering school. And then got a job in tech back in the 80s. I was surrounded by men for decades. So, I had many friends who I never had a romantic connection with. (I dated a total of 5 guys while I was in college/grad school. I had way more than 5 friends.) The ones that I stay in touch with are primarily 4 of the ones I dated, although there are 3 others at the Christmas card level of friendship. Those 4 were the ones I cared about enough to invite to my wedding (one of them came all the way from Brazil to be there!), so I guess it depends on what you mean by "friend".