You could break it up into segments and incorporate them at strategic points in the story. Make sure each segment adds value and moves the plot forward.
Communication is key. Share your fantasies and desires with your partner. It can open up new avenues for both of you in the relationship. Also, keep exploring new things together, like trying a new hobby or traveling to a new place.
Perhaps the tattoo has a special meaning that he wants to keep private. It could be related to a personal journey or a relationship that he doesn't want others to interfere with. For example, if it's a tattoo related to a past love or a mentor who taught him a valuable but forbidden skill. The knowledge of the tattoo could expose these things and he wants to protect them.
Using video call apps like Skype or Zoom is a great way. You can see each other's faces and have real - time conversations as if you were in the same room.
Sending sensual gifts can be a great way. It could be a piece of lingerie or a scented candle. It adds an element of surprise and sensuality to the relationship. Also, planning virtual dates that have a sexual undertone, like watching a romantic and steamy movie together while chatting, can work well. Another thing is to make use of technology like sex toys that can be controlled remotely. This can add a new dimension to the long - distance sexual relationship.