Your question is very similar to one I answered last year from a woman whose boyfriend never brushed his teeth. Take the advice I gave her, multiply it twice (for the lack of showers, too) and apply it you. My advice was this: “It’s not like you’re not criticizing something he has no control over — like, say, a snaggle tooth or something — you’re telling him (I hope) that his breath is funky and he’s putting his health at risk when he skips regular brushing and flossing. For all that’s good and right in this world, don’t ease up on that message for fear of hurting his feelings. If anything, you need to be more clear and more focused is relaying the message. Stick post-it notes on his bathroom mirror reminding him to brush; buy him a snazzy new electric toothbrush, stick some floss in his jacket pockets; and finally, withhold physical intimacy from him until he shows you the respect of cleaning his mouth.”
Yes, I went there: don’t have sex with the guy if he’s not bathing or brushing his teeth! But don’t withhold sex just because he stinks; withhold it because you no longer feel intimacy with him. For the record, you are way beyond “breaking it to him nicely” that he stinks. Is he being nice to you when he skips showers? When he tries to kiss you with his foul breath? No. And you need to let him know that his terrible hygiene not only turns you off, but it has greatly damaged feelings of intimacy between you. In addition to better hygiene on his part, you need dates together. You need attention. You need to connect again. If you aren’t able to do that, not only should you put ideas of engagement on the back burner indefinitely, you should definitely seriously consider moving on already.
*If you have a relationship/dating question I can help answer, send me your letters at firstname.lastname@example.org.