My last bf was a super busy engineer and my current bf is a super busy engineer. I learned from a lot from the mistakes with the first one, but the second one is able to maintain better spirits through his suffering, which also makes it easier.

People with high effort, high stress jobs get depressed occasionally. It's hard for them to unwind. They can't take breaks when you feel like interacting - it can disrupt the flow of their work. They'll come to you or text you back when they're capable of doing so. They also need boundaries. At least 1 day a week of no work, preferably 2. Some nights its unavoidable to work until midnight, but as much as possible, find a cut off point at night for rest and relaxation with your partner.

Don't neglect physical fitness, in fact, share it with your partner. Go on jogs and hikes together on the weekend.

Don't neglect sex. It can be a nice way to unwind. If you're dating the type of person who gets stressed out by work a lot and can't have sex when they are stressed out... that could lead to a lot of incompatibility.

Takes a lot of willpower and motivation to stay happy and stress free on the person who works more, and takes a lot of independence and emotional self reliance on the part of the less busy partner.