Longterm member/lurker here.

Been with my partner for 5+ years, extremely strong relationship, never had serious problems or difficulties communicating throughout the relationship. We have the perfect relationship 99% of the time, including when I'm sad or frustrated, when he's sad or frustrated, etc. But I do really struggle to show my support for him when he is going through stress. When stressed, I find him to be a very different kind of person, and would really like to understand this side of him.

as a side note, we are very different people in terms of work ethic - he is more of a zen person, loves learning, has history of working very hard when needs to but is very much a '8 hours and done' person; I work out of hours and all the time as I am a company director and need to, which leaves me for less time or patience on relaxing.

My partner is at the end of a masters course, the results of which will take him through into an important PhD.
He is having a lot of difficulties with his course, some of which are out of his hands (he hasn't been able to do any work in the past 2 weeks because of technical difficulties out of his control), some of which are in his control (when stressed he procrastinates by watching gaming videos until very late, gets into poor dietary habits). I think the 'out of his hands' problems will be solved over the next two days, but it will involve a very long 5 hour commute every day for the next 3 weeks(!)

I am away on business for 4 days a week for the next few weeks until his deadline at the start of September. I am also away for fun on a trip we planned together with our friends at the end of this week which he is now saying he can't come to because he is stressed. So I'm not here often.

I am trying to gently suggest to him to come out with me and do a few relaxing/stress-busting things like going to the gym or for a walk, eating well and not eating junk, putting his phone/computer away at night so he sleeps instead of watching things until 4am. In my head it's common sense and will really help. But the answer is a point blank no and he sees my actions as nagging which is the last thing I wanted to do, so I have tried to stop this.

What can I do to help? I am considering leaving some healthy meals here so he is at least eating well, but I don't know how to help on getting him out of the house or sleeping properly when I'm not here. (he admits he goes into a 'slug mode' when I'm not here)

I would just like some help to see things from his perspective and try and help him as I'm worried about him failing his course. I totally understand men and women approach stress in a different way and would love some resources on helping with this.