<s>
Couple	O
,	O
formerly	O
Pair	O
,	O
was	O
a	O
mobile	B-Application
app	I-Application
that	O
provided	O
a	O
mobile	O
messaging	O
service	O
for	O
two	O
people	O
,	O
especially	O
romantic	O
couples	O
.	O
</s>
<s>
It	O
is	O
a	O
competitor	O
to	O
apps	O
like	O
WhatsApp	B-Application
,	O
Facebook	B-Protocol
Messenger	I-Protocol
,	O
and	O
KakaoTalk	B-Protocol
,	O
but	O
it	O
is	O
unique	O
in	O
that	O
it	O
is	O
for	O
communicating	O
with	O
exactly	O
one	O
other	O
person	O
.	O
</s>
<s>
Couple	O
is	O
one	O
of	O
a	O
slew	O
of	O
mobile	B-Application
applications	I-Application
that	O
intentionally	O
confine	O
their	O
communication	O
to	O
a	O
small	O
group	O
,	O
as	O
opposed	O
to	O
large	O
public	O
or	O
semi-public	O
networks	O
like	O
Twitter	B-Application
.	O
</s>
<s>
The	O
app	O
is	O
no	O
longer	O
available	O
on	O
iPhone	B-Device
and	O
Android	B-Application
.	O
</s>
