Is this jealousy or are they being territorial?

Me and my husband have been friends with another couple for 22 years,we meet at the pub every fortnight and go on holiday together.They don,t socialise with anyone else except family and neither do we.We,ve never let them down but they,ve let us down a number of times and don't seem to have a concience about it and it always seems to be on their terms.Anyway last year i decided to try to expand my social circle(we know loads of people but no one as close as the other couple)and we met a lovely couple that we have so much in common with who sometimes joined us and the 1st couple for a drink.The thing is cos me and my husband have been on meals out with the second couple the 1st couple are acting jealous and i don't think they have a right to when all they do is pick us up and put us down when they feel like it.The situation is driving me nuts,its like were still at school and its ridiculous.Id like all 6 of us to get on but it's not going to work especially when the bloke out of couple 2 thinks that the bloke out of couple 1 is an arrogant (which he can be).Iknow the answer seems obvious but we do genuinely care about couple 1 although i don't know why.What the hell do we do?