Thanks for your question. I will try to help.
I assume that you are a non-EEA national
As he is Lithuanian, I assume by “ILR” you actually mean “permanent residence” since this is what EEA nationals apply for once they have been in the UK for 5 years or more working. This is the right to stay permanently in the UK.
There is nothing preventing you marrying him in the UK even though you have not lived together. However, the notice period that you give at the registry office may be slightly longer because the home office will be informed of the married.
Once you are married you will have to apply for an EEA residence card as the non-EEA spouse of an EEA national in the UK. The webpage on this is here:
Your fiancé should really inform the home office when he lost his PR card. Normally, he would have to apply for a replacement PR card because he has lost his:
The difficulty is that it takes up to 6 months for them to issue the PR card and so it may not come by the time that you make your application after you are married.
My view is that you should marry and then you apply for your residence card with your husband stating in your application and covering letter that he has lost his and that he will apply for his replacement PR card once yours has been approved and sent.
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