Upvote:1
Being refused a visa is not the same as being rejected entry. UK Border officials can refuse to allow entry on arrival in the UK even if the visitor has been granted a visa; similarly, visa-free nationals such as yourself can be refused entry on arrival if the Border official is not satisfied that the visitor meets the requirements of the Immigration rules relating to visitors https://www.gov.uk/guidance/immigration-rules/immigration-rules-appendix-v-visitor-rules. If you attempt to visit visa-free on the same basis as your rejected visa application, you are likely to be refused entry when you arrive in the UK. If you really need to make the trip (can your BF visit you instead?), your best option is to reapply for a visa, addressing the refusal reasons cited by the ECO. You may want to re-think the intended length of the visit - genuine visitors with strong ties to home would likely find it difficult to be away so long - and provide proof of your relationship eg emails, online chats. You may find it helpful to read this answer UK visa refusal on V 4.2 a + c (and sometimes 'e')
Upvote:1
While your financial documentation may have been questioned, it may have also been the premise of your visit: a boyfriend is usually not someone whom you have not seen in 5 years. Your plan to be there for 5 months may have raised red flags about your real intentions, including how you were going to support yourself and/or whether your available funds were sufficient.
While US citizens are allowed to enter visa-free entry to the UK, now that your have been refused a visa, you run the risk of being refused entry at the border. Border officials will see your immigration record including the visa refusal. Visa refusal and entry refusal are not necessarily the same, depending on the circumstances, but they can impact a future decision on whether allow you to be in the country.
Now, the recommended approach is to apply for entry clearance by making a visa application and amending the weaker or questionable portions (e.g., short visit of weeks not months, demonstrating home ties such as employment).
A read of the following Q&As here may be of use: