to fall out with: to quarrel, to have a conflict.
| He left the party after falling out with his girlfriend.
to get on like a house on fire: people get on like a house on fire when they like each other’s company and become friends very quickly.
| I like my new roommate! We have a lot of same interests and get on like a house on fire.
to get on well with somebody: to have a good relationship with somebody.
| I’m an outgoing person and I easily get on well with new people.
to get to know someone: to become acquainted with someone.
| I thought Jenna was selfish until I got to know her and understood her real character.
to have friends in high places: to have friends in powerful positions in business or government.
| Joe owes his fast career growth to his friends in high places.
to hit it off with somebody: to quickly become close friends with somebody.
| I could not imagine that Laura will hit it off with Dylan! They are so different.
to keep in touch with someone: to maintain contact with someone.
| I keep in touch with my friends from high school, although we graduated five years ago.
to lose touch with someone: to lose contact with someone.
| I lost touch with Mary since she moved to Canada.
to see eye to eye: to agree.
| I think it’s better to live in a big city, but my brother doesn’t see eye to eye with me about it.
to strike up (a conversation, a relationship): to start.
| I feel awkward when I strike up a conversation with unknown people.
ups and downs: a mixture of good and bad things that happen.
| We’re friends for almost 30 years! Surely we’ve had our ups and downs.