To me, that seems bit small for 2 adult Amphilophus,
If already grown, what size tank were they previously in?
In many cases the former size of tank they were in, influences the way they will react to each other in the space later.
but....in the end, no matter what,
the fish will let you know if its adequate.
If they perceive it as not enough, one will kill the other
As an example
I had a pair of Nosferatu bartoni in a 6 ft tank, where they lived peaceably and spawned at least 3 times.

I then gave them to another aquarium club member ( they were small, only @ 4".
He put them in a 4 ft (110cm tank).
The next morning the female was dead.