Have a tendency to exaggerate / lose his/her temper / make snap (quick) decisions

Meet through a friend
If someone has "met through a friend" that means that they are in a relationship with someone that they met because they have a friend in common who introduced them to each other.

Set people up
To "set people up" means to tell two people that they should date each other.

Treat
To "treat" means to pay the cost for another person's meal or activity when on a date.

Invite
To "invite" someone means to ask them to do something with you.

Chat up
To "chat up" someone means to have a casual conversation with someone in order to get to know them better.

Flirt with
To "flirt with" someone means to talk and act a certain way in order to make clear to them that you are attracted to them.

Break up
To "break up" with someone means to end your romantic relationship with them.

Split up
To "split up" with someone means to end your romantic relationship with them.

Fall out
To "fall out" with someone means to not agree with them about something and to have bad feelings for each other as a result of it.

Have a fight
To "have a fight" with someone means to not agree with them about something and to have an argument over it.