declaring if you have a partner or not for universal credit with LCW

hello,

I am a bit confused about the universal credit guidelines around single / joint claims.
they state that if you are married, in a civil partnership or live as married then you need to make a joint claim... what about if you have a partner but don't live 'as married' as in, it would not feel normal / possible for your partner to sustain you financially or share their savings with you, you don't have a joint account or any agreements around sharing assets...

I have limited capability for work, am self employed and on UC. If I had a partner who had some savings and a relatively well paid job, would I still be entitled to the same UC support? or would the assumption be that my partner would have to support me financially, and so I would receive little or no UC?

What concerns me about this is that it would put a lot of strain on a relationship (especially if you haven't been in a relationship very long) and remove the small sense of independence I get from UC. It would also probably push me to work more than I have capacity to work with my mental health condition, which would also increase stress and worsen my condition.

I would be really grateful for any insight or other experience with this,

Thanks