No you're not in the wrong he is you get idiots in all things he just happens to be on bike.
As cyclists we love seeing someone learning how to ride it's how it all starts after all. Many of use if we'd been following on a bike would have had a word or two to say to him.If it's the same bloke at the same time I'd be having a word or time it right so you and your her can enjoy the time together. If you can practice at a park or something maybe that's worth a go as you don't want some loon putting her off going out.
Is he a neighbour or just pass though? If he is local then a friendly word from police will help.
Keep us informed of how you get on and if you need any help or advice helping her to get use to things.
We are a friendly bunch and always willing to help.