From Longman Dictionary of Contemporary Englishit’s just thatit’s just thatREASONused when explaining the reason for something, especially when someone thinks there is a different reason No, I do like Chinese food. It’s just that I’m not hungry. → just
Examples from the Corpus
it’s just that• She says it's because the water is pure from the mountain but she doesn't really believe it's just that.• He's not ugly or anything. It's just that he's too short for me.• Nothing drastic - it's just that his studio is taking on a more Tardis-like appearance than before.• I was not supposed to clean there, it's just that I love reading and sometimes I feel starved.• Business or hatred, there's something that stays the same - it's just that person; just about him.• But I think it's just that the winter weather keeps the birds away.• Or maybe it's just that there is a course that teaches advertising and marketing, which is relatively new in itself.• Maybe it's just that those who don't look don't survive to tell the tale.• Perhaps it's just that we don't have enough of those long, thin granite cracks. 