There are probably a bunch more questions you need to ask yourself. Are you looking to tow the XJ across town? Or to Moab? Will this be a once every 5 years sort of thing? Or several times a year? Are you fine with being the slow guy that has 20 cars backed up behind him? Or are you a leadfoot who is likely to be passing cars with a loaded trailer in tow?
There is probably more than that, but those should help with the perspective.
Everyone has their own comfort level, and towing is one of those places where different folks have very different risk thresholds. My own tow rigs are a 3/4 ton big block Suburban and a Cummins dually. Either of those is comfortable with an enclosed car hauler with an XJ inside. But the guy I bought the enclosed car hauler from had towed it all the way across the USA behind his small (in my mind) Ford SUV (I can't recall if it was an Explorer or the next size up, but the trailer sure dwarfed his tow rig). He had towed it with his Model A street rod inside it, so a fairly light load, but the combination of trailer and street rod was certainly more than an XJ. He admitted it was slow over the mountains, and he took his time doing it. But this was also a once in a lifetime sort of job, not something he planned on repeating on a regular basis. I on the other hand proceeded to rack up almost 30K miles on that trailer over the next 12 months, with lots of mountain passes, heavy loads and long days. What I did would not have been reasonable with his tow rig.
Point being, your answer is going to come down to you and your expectations and comfort level.
I would suggest looking for forums specific to the vehicle you are looking at and searching for threads about towing. I would also inquire about towing packages at the dealership if looking at brand new vehicles. Hopefully a towing package will be more than a wiring harness for a trailer plug. Ideally it will be an upgraded transmission, cooling system and larger brakes. At least that is what I would want to see. Most likely it will be a transmission cooler. But ask.
I would avoid Honda and Chrysler products for towing on the basis on their inability to come up with an automatic transmission that can handle heat (My Cummins is a manual--I don't expect you are looking at that sort of animal). I would also suggest you pay close attention to load ratings on tires. My 3/4 ton Suburban came to me (used) with load range "B" tires on it. Pathetic. It now has the load range "E" tires that it should have had all along. Evidently a previous owner didn't have any need for load capacity. I do need that capacity. Again, it comes down to the individual user.
One other thing: If you are new to towing then you need to get acquainted with the nuances of trailer wiring. Do a Google search for "The Art of Trailering" by Patrick F. McManus. It is a available as a PDF. You must read this. All the more important given the fact that your are currently married. Know what you are getting into.
Best of luck.
FWIW, The Bride and I just celebrated our 25th anniversary, so this can be survived.