'That should be fine' instead of 'yes'

[Kendra43]

What is the difference in these two phrases to you?

Lately my partner has been agreeing to do things with the phrase 'that should be fine'. Recently he lets me down after saying this.

It has happened again where we agreed to a plan last week for tomorrow. This morning I clarified if he's still good for tomorrow and he says 'that should be fine'.

Because this is what he says every time he does let me down I'm annoyed. I feel that by not saying 'yes' he is not fully committing to our plans on some level to himself.

AIBU to say this is a phrase non committal people use? Or does it mean the same as 'yes' to you?

I have found myself typing this recently but then realised it isn't clear or useful communication so alter it to reflect what it is I actually need to check before committing. So to me it definitely doesn't mean yes.

Got to be honest … if someone asks me to do something that I don’t particularly want to do but don’t know how to get out of it I would say ‘I’ll let you know’ or ‘should be fine’…..
then I’d either later make an excuse or decide to grin and bare it…
sorry OP but I think you need to consider whether you’re the one putting in all the effort and making plans and whether he’s just not that bothered or committed 😭 sorry