Yes ofcourse. That was why I asked. I wanted to know if it would be counted as an overstay or not.
Sorry if this was not clear in my original question.
As long as you leave the UK within the 6 months allowed by your visitor visa, you would not have overstayed.
However, the issue is with trying to return for another stay right away... because that will likely look like you are trying to use the visitor visa to 'live' in the UK, which is not allowed.... and so there's a good chance that you would be turned away at the border and not let back into the UK (this is not an overstay, just a refusal of entry).
If you were to be let back in again, then you would be allowed to stay for the length of time that the immigration officer gives you permission to stay... usually this is 6 months, but it is at their discretion. If they feel you are an overstay risk or that you are using the visitor visa to live in the UK, they can let you in for as little as 1-2 days, or maybe a few weeks - and they might keep your passport to make sure you leave on time. It would depend on their decision on the day.
But do I really need to be gone 6 months if I was here 6 months? I was hoping for maybe 2 or 3 months and then come back and marry within 2 months.
How would they see that?
There's no definite rule, but ideally you want to be spending MORE time outside the UK than inside the UK. Because they will look to see exactly how much time you have spent in the UK in the last 12 months and how much more time you are trying to stay for and use that to determine if you are attempting to 'live' in the UK.
If you have already been in the UK for the last 6 months and then you ask to come back in for another 2-3 months, that would be a total of 8-9 months spent in the UK in the last 12 months... and only 3-4 months spent outside the UK. Therefore they may well determine that you are trying to spend too much time in the UK compared to the US.
But, if you were to wait say, 7 months to come back as a visitor, then you would have spent 6 months in the UK and 7 months in the US... so, more time in the US than the UK in the last 12 months, which doesn't look so much like you are trying to live in the UK as a visitor.
Bear in mind though, that this does NOT apply to fiance or spousal visas, as those visas allow you to legally live in the UK. So if you were to leave the UK in January and apply for the fiance visa right away, you can come back as soon as you get it... no need to wait.
What they look at when making the decision as to whether you have spent too much time in the UK:
Frequent or successive visits: how to assess if an applicant is making the UK their main home or place of work
See: paragraph V 4.2(b) of appendix V: visitor rules.
You should check the applicant’s travel history, including how long they are spending in the UK and how frequently they are returning. You must assess if they are, in effect, making the UK their main home.
You should look at:
• the purpose of the visit and intended length of stay stated
• the number of visits made over the past 12 months, including the length of stay on each occasion, the time elapsed since the last visit, and if this amounts to the individual spending more time in the UK than in their home country
• the purpose of return trips to the visitor’s home country and if this is used only to seek re-entry to the UK
• the links they have with their home country - consider especially any long-term commitments and where the applicant is registered for tax purposes
• evidence the UK is their main place of residence, for example:
o if they have registered with a general practitioner (GP)
o if they send their children to UK schools
• the history of previous applications, for example if the visitor has previously been refused under the family rules and subsequently wants to enter as a visitor you must assess if they are using the visitor route to avoid the rules in place for family migrants joining British or settled persons in the UK
There is no specified maximum period which an individual can spend in the UK in any period such as ‘6 months in 12 months’. However, if it is clear from an individual’s travel history that they are making the UK their home you should refuse their application.
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/827480/Visit-guidance-v9.0ext.pdf