Yes, aintfoolin, that's what I meant. She saw the reunion; if she had been less shocked and iincapable of understanding and dealing with what she'd seen she might have realized that jAck was a threat she had to try to counter, and she couldn't do that by just letting Ennis walk out with him and casually say that they might be out all night.
And while it's true that love isn't a game, though the pretence of love can be, sex is certainly a game, though I think not one in which Alma was a very savvy player.
I think Alma's reaction (or lack thereof) in letting Ennis go off with Jack was also partly to do with the way marriage worked in those days, the man was "in charge" and the women just had to put up with it, if Ennis said he was going out and staying out all night, it wasn't Alma's place to question it. Like in the grocery store, where Ennis's job has to come before Alma's, because he's the man so his job is more important

It would be very different in this day and age, thankfully

Having said that, Alma does attempt to confront the situation the following morning, after she'd had all night to think about it, by suggesting Jack come in for a coffee, but of course Ennis was having none of it, though I think that's just because he didn't want to waste any more time than was absolutely neccesary before going off with Jack, rather than because he thought Alma might have some sort of ulterior motive. And in the longer term, Alma does start to stand up for herself more after that, like when Ennis wants her to stay at home and she just ignores him and goes to work anyway. I think Alma thought if Ennis wasn't going to behave like a "proper" husband, why should she behave like a "proper" wife.