It's so disappointing when, like you said, the one person in life you feel like you should be able to turn to for support and celebration, either just isn't available, or seems to actively make things worse. To have that happen over and over again would wear on anyone
It does seem like BPD traits and behaviors can increase around "high emotion" events such as holidays, birthdays, anniversaries, medical incidents, etc. There are many stories here about a member being sick, and the pwBPD really falling apart/escalating dysfunctional behaviors. I wonder if for pwBPD, they fear "emotional support abandonment", as others' emotions and focuses (foci?) are directed elsewhere. "Who's paying attention to me? Have I been forgotten? Do I matter too?" Without inner resources, it certainly makes sense that pwBPD would feel "abandoned", because they are so low-skill in terms of self-soothing. It's a tragedy that BPD so severely limits the person's ability to provide appropriate support to others... it takes a significant toll on close relationships.
So it's not surprising to hear that your H not only has a cycle/timeline, but also seems to escalate around high-emotion times. He sounds pretty limited in his capacity to regulate his own fears and use appropriate tools and skills.
Seems like there are two things to look at: getting through the immediate short term, and decision making long term.
You have from now through June (short term) to get through these moments in a way that is "less bad" -- using your own tools and skills and self care to do what you need to do without adding gas to the fires. That doesn't mean it'll go smoothly, it probably won't, not entirely, but for the next few months, it may be more effective to accept "this will be difficult, and I will do my part not to escalate things, regardless of what he does".
I think you're right to assume, going into this season, that he is so significantly limited that he will not be a reliable source of support. Yes, the bigger question (for later) is -- do you want to be in a marriage with someone that limited, and it's a fair question. For now, though, short term, it may help to
radically accept that this is how he'll be, and find the support you need elsewhere. In fact, you are welcome to start a thread about your business successes, reunions, and retreats here! I think we'd all love to hear how they go, and it's such a diverse group that you'll find others who have had similar experiences and can understand your stresses and triumphs.
Short term, again, some pwBPD seem to do better with tangible reminders/reassurances of your return. For example, leaving an item of yours with him (shirt, picture, collage, stuffed animal, etc) so he has something to look at and feel while you are temporarily away. I hear you that he has an episode coming on, so it may be difficult to find "down time" to have a conversation near baseline about that idea.
There may be other short term approaches that "speak his language" about reassuring him of your return. Again, this isn't about "now you have to do this forever", or "he gets to be babied/coddled/placated", etc. It's about: what will be effective for getting the two of you through the next few months, in the "least bad" way possible, that isn't accidentally escalating. You know him best, so you'll know what might speak to him.
My thought about long term decisions, such as remaining in the marriage or not, is: how about getting through the next 3 months, and allowing yourself to look at that decision then, vs trying to sort it out now. I wonder if you may have more emotional resources/energy, and be at more of an emotional baseline, after June. It's difficult to be in a
balanced, grounded headspace with so much going on... just an idea for gifting yourself one less thing to have to solve right now, with so much else happening.
Part of me wants to give myself an ultimatum - if he can't support me during these most important events, it will finally be time to leave. I want to be with someone who is excited for me - who can support me in challenging and stressful times. Who understands when I need to take my attention off them and give it to other people and things before returning it to them (where it is most of the time anyway). But I guess I can't expect any of this with someone with BPD?
That could certainly be a fair and valid
boundary (internal rule for yourself/your own life), that you choose to be in relationships with persons who support you, and you choose to end relationships that don't offer the support you need.
It's also good that you recognize that BPD is a significantly impairing mental illness. Expecting him to support you like a non-BPD person would be unfair. That doesn't mean your boundary is unfair -- we can have whatever rules for ourselves we want, that align with our values -- it just means it would be the worst of both worlds to both tell yourself "I won't stay in a relationship like this" but to have expected him to "act normal".
Maybe over the next 3 months, you can make some neutral observations about how things go, and use that as information to help you make some wise decisions. It could be that you find a way to accept his severe limitations and receive support elsewhere, and that is "workable enough" for the two of you. You may also find that you need your spouse to be your biggest supporter (a valid need), and that is not happening here due to his deeply relationally impairing mental illness, so you choose to end the relationship.
No right or wrong choices... just ideas for getting clarity about your needs and values.
Really sorry you're going through relational stress during this season of your life.
