Do you always issue return invitations to lunch/tea etc?

[dinny]

Or have I just been misfortunate lately...?

Yes I would.

On the whole yes, although not always every time for closer friends and not for family.

Infact have just invited DH's work contact/friend and his wife over for dinner in March, after we went over to their house in January.

difficult though, isn't it? we have friends who we owe three times now. such narrow windows of socialising