You wrote that you feel obligated:

- to have sex with him (but you also kind of want to, on your own and not due to feeling obligated)

- to have unprotected sex with him (but you clearly do not want to)

So, from that you want to have sex with him you can derive the beginning of a steamy text message (conveying that you want him), and from your clear policy on condoms, derive the ending part of that same text message. e.g.

"HIS NAME...cannot wait to see you (or its less euphemistic equivalent)... do be sure to have condoms on hand please, will you?!!"

The "on hand" part was an unintended pun.

The point is, rather than just communicate dryly and matter-of-factly, add the "cannot wait to see you" - the request for condoms will be better received then.