A bit of a 'What-If' situation has cropped up in our group. Nothing that has caused any table drama, mainly something that has been noticed by some, and debated at the table off-line and casually, but may in fact stand a feasible chance of coming up during session, so some other eyes on the situation could be helpful to avoid a potential halt at the table.

The scenario is as follows:

Wizard casts Invisibility at 3rd rank to encompass himself and one other party member (We'll say the Fighter).

We all know if Fighter attacks, he's no longer Invisible, that's fairly straightforward.

The point of debate, however, is if the Wizard casts a non-concentration spell, ending his invisibility, would they or would they not lose concentration on the spell and also subsequently cause it to end on the Fighter at the same time?

One side of the table contests that it would not end for the Fighter because while the effect of the invisibility ends for the Wizard, it does not make sense that the spell overall would immediately cease to provide the benefit if there was no logical reason why Concentration would be broken, and the first line of the spell,

"A creature you touch becomes invisible until the spell ends."

Means that they simply lose Invisibility, and nothing else, meaning if it really worked out, the Wizard would be Concentrating on a spell that is currently providing no actual benefit, but the spell isn't technically over.

On the flip side, the other side argues that the text of the spell, specifically the last sentence,

"The spell ends for a target that attacks or casts a spell."

Would mean that the moment the Wizard casted a spell, the Invisibility as a spell, regardless of how many Creatures were affected, quite literally ends and Concentration is broken, revealing the Fighter, as the Wizard was a target of the spell and the text states that spell would end if they casted.

In short, the debate seems to be the definition of what exactly "The Spell Ends" means in this scenario; that merely the spell's mechanical effect ends, or that the literal spell-slot consuming ability ends as if Concentration was broken.