As per my comments, it would be unwise to solicit the sale of
example.com directly to the owner of
example.net, as that might be interpreted or argued as a sign of bad faith, and/or that you don't have any legitimate interests in
example.com, which are two of the three elements necessary for successfully wining a Uniform Domain-Name Dispute-Resolution Policy (UDRP) case.
It's unpredictable as to how the owner of
example.net might respond to such an offer. They might feel they have the rights to the domain since they hold a trademark for the keyword in their own country. Or they might just make a business decision based on economics if they'd like the
.com version of their domain...
Consequently, if the offer for the domain is more than the cost of filing a UDRP case plus legal expenses, they may opt to do that, with the hopes that you might also bow to their pressure.
Without the direct solicitation however, it doesn't sound like you are using or registered the domain in bad faith, and that you had legitimate interest in it (which would be supported further if you could show evidence of a site or plans for one).
In terms of the trademark filed in their own country, I'd suggest doing a trademark search to confirm that is the case, or consult with an attorney who specializes in trademark law.
In any case, it seems unlikely that all three elements could successfully be demonstrated, if you avoid the direct solicitation which could put the element of bad faith in jeopardy.
Of course we are not attorneys here, so I'd suggest contacting one if you feel the domain has significant value and would like to sell it, but are concerned about the trademark issues, or contract & terms for the sale should it proceed to that point without the assistance of a domain broker.