Is it possible to catch covid again within 90 days

[123456LA]

I've just tested positive on 4 lateral flows (because obviously one or two wasn't enough for me to do!) Waiting to go for my PCR test.

My partner who has already had covid within the last 90 days (October) has been with me recently (but we don't live together) and has been testing negative. I just wondered what the likelihood of him catching it again within the 90 days would be, what with these new variants etc? Or is it the case where you're still technically 'immune'

I was hoping to be immune but it's looking like it's possible to have both strains.
Dds bf just tested positive and he had Delta when we did, just over the 90 day mark.

DS had it 6 weeks ago and seems to have it again. Presumably different variants.

It’s possible - sorry