When you enter Thailand, you fill in one of those white arrival cards (TM 6). Immigration can be very efficient at finding those when they want to be.

I had a mate a few years back had his passport stolen, and wanted to get a copy of it. He said he went to immigration and it took them only minutes to find it.

Now if OP has the same surname he could try the same route, by going to immigration showing his ID and asking for a copy on his wife's behalf. Maybe have to give a reasonable reason and say she doesn't want to or can't come herself. Strictly speaking they might insist she collects it in person, but if you're particularly nice and friendly, smile a lot, and polite, explaining how you really need it, they might be helpful.

This may not prove she's been there all the time, but it would prove an entry date, which may give the discrepancy wanted already. It also shows passport number and intended duration of stay

Fletch

... Thinking about it you could probably also ask for a copy of the exit card to when someone leaves too if you know the card number and have a reason or copy of the entry, so could end up with a matching set

As someone said above, I'm not sure that it would change much in the end, and may just prolong the inevitable. Often better to solve amicably if you can.

It may show something about the character of the person in question though, if you were looking for a defence to accusations made against you though, and it couldn't be solved amicably.

The action has been commenced in Switzerland.

The OP must therefore engage a Swiss counsel.

He or she must then file a subpoena and have it served on the wife. The subpoena will request certified copies of her passport, account statements, and any other records of interest.

Prior to serving a subpoena the OP's counsel may try to retrieve the required information by way of a request for further and better particulars but these are seldom very successful.

When you enter Thailand, you fill in one of those white arrival cards (TM 6). Immigration can be very efficient at finding those when they want to be.

I had a mate a few years back had his passport stolen, and wanted to get a copy of it. He said he went to immigration and it took them only minutes to find it.

Now if OP has the same surname he could try the same route, by going to immigration showing his ID and asking for a copy on his wife's behalf. Maybe have to give a reasonable reason and say she doesn't want to or can't come herself. Strictly speaking they might insist she collects it in person, but if you're particularly nice and friendly, smile a lot, and polite, explaining how you really need it, they might be helpful.

This may not prove she's been there all the time, but it would prove an entry date, which may give the discrepancy wanted already. It also shows passport number and intended duration of stay

Fletch

If she has a Swiss passport she will more than likely have a Thai one she can use that for leaving Thailand and the return and the Swiss one entering and leaving there so would not have to fill out a white card. Just a thought.

When you enter Thailand, you fill in one of those white arrival cards (TM 6). Immigration can be very efficient at finding those when they want to be.

I had a mate a few years back had his passport stolen, and wanted to get a copy of it. He said he went to immigration and it took them only minutes to find it.

Now if OP has the same surname he could try the same route, by going to immigration showing his ID and asking for a copy on his wife's behalf. Maybe have to give a reasonable reason and say she doesn't want to or can't come herself. Strictly speaking they might insist she collects it in person, but if you're particularly nice and friendly, smile a lot, and polite, explaining how you really need it, they might be helpful.

This may not prove she's been there all the time, but it would prove an entry date, which may give the discrepancy wanted already. It also shows passport number and intended duration of stay

Fletch

If she has a Swiss passport she will more than likely have a Thai one she can use that for leaving Thailand and the return and the Swiss one entering and leaving there so would not have to fill out a white card. Just a thought.

Thai passport holders also have to fill out the same TM6 forms on leaving and entering

Fletch

The action has been commenced in Switzerland.

The OP must therefore engage a Swiss counsel.

He or she must then file a subpoena and have it served on the wife. The subpoena will request certified copies of her passport, account statements, and any other records of interest.

Prior to serving a subpoena the OP's counsel may try to retrieve the required information by way of a request for further and better particulars but these are seldom very successful.

The wife is Swiss. She probably doesn't even need to be domiciled in Switzerland to divorce a Swiss marriage, and possibly could do it with power of attorney. The OP will need to find a better way to resist divorce and/or protect assets.