Location: California
Hi all, I'm not sure if this is the best subreddit since it's kind of an immigration/border question. My partner of a little under a year and I live on the US-Mexico border; he's about 15 minutes from it on the Mexico side, and I live on the US side. He works as a dentist there and has no intention of immigrating to the US as he already works in a well-established clinic there and loves his job. I'm considering moving there with him at some point in the future, but not for a little while as I'm still in school. We travel back and forth to visit each other often; one week I'll go down, and the next he'll come up. He has a tourist Visa and SENTRI, and when he comes up he'll stay for like a night or two maximum but then will leave back to his place there.
The last couple months he's visited a little more frequently than usual; he's had a few friends' birthdays here and also a couple concerts that he had tickets to, but each time he leaves the next day. In total he's crossed 6 times in the last month, never staying more than a night. The last few times he's crossed, though, the CBP officer stopped him and asked a lot of questions about why he's been coming up so often. Yesterday he was told by the officer that he's coming way too frequently, and that he's not supposed to be staying overnight and is expected to leave the same day. From the sound of it, they seem to think that he's secretly living and working in the US. He's really scared that they're going to revoke his Visa over it.
I get that that does happen and people do sometimes overstay their Visa, but I'm not clear on what the actual rules are about how frequently you can visit or what it would take to prove that he's not living here. He spends the vast majority of days in Mexico and isn't interested in working in the US. I would have thought that the burden of proof would be on them to prove otherwise, but maybe that's naive when it comes to immigration/border law (especially in the current environment). Is there some way to make this look less suspicious, or some guidance on how often is too often?