Make friends.
Fall in.
Stop being friends.
Fall out.
Know somebody better.
Get to know somebody.
Like/enjoy the same things.
Have a lot in common.
Not stay in contact.
Lose touch.
Like to be with somebody.
Enjoy somebody's company.
A person one knows slightly, but who is not a close friend.
An acquaintance.
Understand each other well.
Be on the same wavelength.
Find the same things funny.
Have the same sense of humour.
Stay in contact.
Keep in touch.