"snap" Oh, How I Sympathise with you. Happens to me on a regular basis. I do not like weddings, As a business you do them for the revenue, but if you could be a profitable photographer without doing weddings I would still be one. I have not been a "Pro" for a couple of years now and have done 3 weddings. Every time it is friends that invite my wife and then say: ask Simon to take some pictures, will you???
I have just last week been talked into a wedding for July 2018. People have no idea how much work goes into photographing a wedding. The last official wedding I did not wanted to do, I asked for 2K upfront, thinking that will scare them away and ended up with the money and a commitment to do the work, so that did not work out. I now go for the honesty option and that worked out well. I ask if I was going to get invited to the wedding if I was not a photographer, if they say no, it is quite easy to tell them to get a pro wedding photographer and I give them some contacts. They cannot be that close a friend if they do not have you on the invite list. If they say yes, it is quite easy I will thank them and say I would really enjoy it, but if I take my camera I can not enjoy the wedding so I give them some contacts.
If your wife wants to go you are snookered and you best charge your batteries. You do not need the best latest equipment. Capturing the moment and the mood can be done on most cameras.