I'm sorry, but I don't get those who are willing to "forgive" him if he 'agrees to knuckle down for another season' like Suarez did. I can't really see him doing that (or should I say, to the effect/extent of Suarez).
The Suarez situation was different. When we (apparently) made the proposal, the (only?) official bid at that point in time was from Arsenal, a domestic league "rival". It was evident that for a player of his talent, the bigger foreign clubs will come calling with another brilliant season of football (the season before his last was the first in which he was truly prolific - 30 in 44 app, the previous season 17 in 39 app). There was also obviously his on field issues (which he might have felt a little sorry and wanted to 'repay' us).
In Coutinho's case, who else will come calling + offer the amt of money that's being mentioned? I can only think of PSG. The moment he threw his toys out of the pram (albeit indirectly), the only thing I was concern about is getting the best possible deal. Call me stupid unless that 1 extra season's going to increase his valuation (like Suarez's case), I don't see much point. It should be pay up (Barca) or honor your contract (Coutinho) - no "promises" from our side.