a person who is in the same class as you
classmate
to have the same interests, experiences, or qualities as someone or something else
to have sth in common / have mutual interests
your friend in other words
a buddy, a pal, a mate
a person that you share a flat with
a flatmate / a roommate
two people who are married or in a romantic relationship
a couple
a very good friend that you can talk to about anything
a close friend
you meet somebody, yo have things in common and you spend time with them.
become friends
to begin a legal relationship with someone as your husband or wife
get married
end a relationship
break up
the person you are engaged to be married to
a fiancé male / a fiancée female
you husband, wife, boyfriend, or girlfriend
a partner / a SO - a significant other
ask someone to marry you
propose