Getting married

An Irish guy tells his mum he's going to get married then he says "to test you I'm going to bring 3 girls round and I want you to guess which one I'm going to marry"

So he brings 3 beautiful girls home for tea. After an hour he says "well Ma which one I'm going to marry" without hesitation she says
"the one in the middle"

"That's amazing" he says "but tell me how did you know?"

She said " it was easy

Spoiler:

I don't like her!"