PPD in dads

Hey, so it’s my first time posting on here but just looking for some advice really. Myself and my partner have been together almost 4 years and have a 5 month old baby. Throughout my whole pregnancy it was a little bit rocky as baby wasn’t planned and made a lot of things hard for us both. A couple weeks before giving birth my partner finally came round to having a baby more than to begin with. However, since having our baby things have been a little hit and miss; arguments over small things, struggling to adjust still (which of course I know is completely normal - it’s a huge change!) but I feel like he may have PPD as everything makes him feel so low at the moment. How do I help him as dad? It’s not a commonly spoken about thing with dads as much as it is mums and I just feel so helpless! Thank you all so much 🤍