30 years old...why is it so hard to make new friends at this age?!

Over the past 5 years, I’ve lived in 6 different cities due to work and school. Over that time, my friendships have suffered a little bit as a result. None of my friends from high school or college live close and i often feel lonely. Ive tried making friends through work but they always make excuses or ignore my texts. I understand that people grow apart, especially when you live further away but I feel rejected by women my age. Is that just what happens as you get older?