Lior – many divorcees have exes who refuse to pay towards their own children’s weddings. Don’t think that does not happen all too often. Sometimes the burden of cost is falling solely on the one parent (usually, but not always, the mom). When you see a father refuse to chip in for his own children’s simchas, tuition, orthodonture, etc. his laissez-faire attitude may even be one of the reasons that the marriage initially failed. No one but the two people involved really knows the truth.
As to divorcees being offended at being invited or asked if they need help – SERIOUSLY??????????????? There is pride, and there is foolish pride. But if someone says no to an invitation, then try again at another time. And keep trying.
My next door neighbor was widowed recently, lo aleinu, and I invited her to join us for Shabbos meals. She has been going to her son, and said thank you, but she is usually going to be by them. My response? “Enjoy your aineklach whenever you want to be away by them, but I am giving you an open invitation to simply show up at my door Friday night and Shabbos lunch, as often as you like. You don’t need any formal invitation from me anymore. You are always welcome by my Shabbos and yom tov table, just make sure I’m home. And I mean it!” She really appreciated that.
Don’t stop inviting someone just because they said no (unless you are uncomfortable with them, for some reason). Sometimes they need to see you really mean it. It is not being a nebach, it is called v’ahavta l’rayacha kamocha.