When you say "proof of living with your spouse during the duration of the visa" are you talking about the fiancee visa or the spousal visa? I'll be living with him a bit before our wedding and after, and I have a bank account there that will send me mail to his flat. I just want to return to the US and get the last few weeks of income before we're married. Is there anything else I'd need?
As UKVI will be able to see that you've exited and re-entered the UK during the duration of the fiance visa, you'll need to explain why you weren't living together during that time. I suspect that returning to a job in the USA will be "okay". I would try to limit it to a matter of weeks though, not months.
Yes, you will need proof of living together during the duration of your fiance visa. Supposed to be six items of post addressed to you jointly or 12 individually during that time. If you are unable to provide that, you'll need to explain why on the FLR(M) visa.
But yeah, we don't like lawyers. This lawyer is costing you guys a couple of extra thousand ££'s versus if you had done a marriage visitor visa. You wouldn't need those few extra weeks of work if it wasn't for his/her advice.
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