Thanks for all the replies folks. I think you're right about the insecurity thing although I don't understand why. Some more information - My ex I saw the other day because my daughter went to see her (she likes to keep in touch) and I had to go and pick her up from there. Apart from that I haven.'t seen my ex in Jan and that was because I bumped into her by accident. I don't see my ex, don't call, don't try to get her to go out with me or anything. So I was annoyed by my GFs seeming lack of trust in me - since I"m 100pc faithful.
But we talked and resolved the problem. Yep, if my GF wants to be there when the ex comes for her cuttings then of course she can be there.