Hi, I'm very new to this and have several questions.
one being that i'm in a semi Poly relationship I guess... I don't actually want to go out and be with anyone else but my guy. he however wants/needs more and is seeing someone once a week.. I'm ok with this. my question is: is it wrong to make him wash the sheets/duvte cover even if they have only been on the top of the comforter?
Hi,
Erika, and welcome!
Ignoring, for a moment, your actual question

, there are some more important aspects to address:
a) As far as I know - or can imagine - there is no such thing as a
"semi Poly relationship". Either a relationship is poly... or it isn't. A poly relationship does NOT oblige the members in it to have other sexual partners. It DOES mean that all members of it respect the others' right to enter into emotional relationships with others. It demands good communication and honesty. It does NOT forbid jealousy.
b) Your guy may define himself as poly. you may define yourself as either poly [you agree with it 100% and might find yourself someone else in the future, but don't fancy doing so now] or mono [are perfectly happy with just one guy, would never date anyone else, but are happy for him to do so].
c) Let others correct me if they will, but - in my opinion - if you
"are happy for him to do so", then you
as a person might be mono, but you have a poly relationship with him.
d) In fact you are in a poly relationship with your guy's partner as well. The 3 of you form the famous (and very common) poly relationship: the V. Your guy is the "hinge" of the V. You and the other are each other's "metamours". You may - but are not obliged to - get on well with your metamour.
e) Now to your question... but in more general terms: You have a right to ask
anything of your guy... and he has a right to refuse your request. If you want this thing to work, understanding, mutual respect, and a bit of give-and-take are essential.
A much more common request than yours would be "I don't want you guys doing it in/on OUR bed" - or even "... in our house". [Some] poly couple with years of experience have this rule, and it works fine for them. Because all the parties involved respect the personal space of each other.
Back to your specific question: If his washing the sheets is
really important to you and he ignores your request (or treats it with disdain), he is not respecting your wishes and needs, and you're going to run into trouble.
But you need to
talk with him about it to find this out. (Good communication.) If you keep silent, but are really resenting the fact that he doesn't wash them, that's
your problem to deal with. (The keeping silent and seething, I mean.)
Question answered? Any more? One for you. Give it as much weight as you wish, and believe me when I assure you that it's not meant judgementally: Are you sure that you're OK with his having another relationship... or are you allowing it so that he won't get upset at you? Poly isn't for everyone and you might discover that you're happier in a mono relationship. (With your guy or someone else.)
Is it your bed? If it is and your boyfriend uses it for sex with his other, then - whatever level of hygiene is comfortable for you is right.
No difference to me: If you are unhappy about the hygiene of
his bed, you still have the right not to sleep (or do anything else) in it. But you're going to have to deal with that honestly. (Even if there were no other person involved: you have the right to deal with questions of hygiene at his place.)