I had a lifelong friend (since 6 years of age), and we would hang out for extended periods of times at different phases of our lives. But then, in our forties, he just stopped keeping in touch.

I tried to keep the friendship going, but for some reason he just decided that he didn't want to be friends anymore. So, you could approach them, I would say, but also be prepared that sometimes people just lose interest.

It has nothing to do with you and please don't blame yourself or feel too bad about it. Sometimes I think it just happens as a "fact of life." But I wouldn't give up on them just yet, until you give it some more time....