Waking up multiple times a night

My boy is about to be 6 months and the past week has been horrible with him not sleeping long stretches at night. Getting him consistent naps during the day can be rough. On a good day: wakes up between 7:30-8:30, maybe takes 30 min nap around 10-11, usually takes his long nap around 1:30-3. And the rest of the day is just not consistent until getting ready for bed at 9. 3/3/5 is probably the most accurate.

My partner really wants to sleep train him and doesn’t think I should get him right away cause he won’t learn how to fall asleep on his own. I’ll let him cry a little, but it’s almost impossible for him to sooth himself. I can barely soothe him. He has to have a bottle to fall asleep and will not take a pacifier. We’ve tried so many times but he spits I out and makes a disgusted face. My partner can also sleep thru his crying so it’s not like it bothers him at all 🙃

I’m not sure if this is the sleep regression, teething, or just going thru separation anxiety. He used to be so good during the night and I’m at a loss.