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